Backyard Aquaponics in the Northeastern U.S.-- Update on plants 08/10/2014

[C-4]

New Hampshire Backyard Aquaponics -- Preparations for Spring 2014

Greetings everyone,

I have an aquaponics thread I started on AR15.com in the summer of 2012. derek saw it over there and invited me over here a while back. Great site BTW. My aquaponics thread is still ongoing over on AR15.com, but I am going to make some significant changes and I'd like to document them here for your enjoyment and education as well. There are likely others here who are also doing this and can both add to the discussion and provide constructive criticism.

First, a quick definition of aquaponics that I borrowed from here.

Aquaponics is the cultivation of fish and plants together in an constructed, re-circulating ecosystem using natural bacterial cycles to convert fish waste to plant nutrients. It's a natural food growing method that harnesses the best attributes of aquaculture and hydroponics without the need to waste any water or filtrate or add chemical fertilizers.

Aquaponics in the northeast is unique for several reasons including: wide fluctuations in temperature, the types of fish and plants that can be grown, and the fact that the system needs to be "shut down" during the winter due to freezing temperatures unless it is brought indoors or at least into a greenhouse and additional heat supplied. For my aquaponics system, I will not be bringing the fish indoors, but instead, if all goes well, will allow them to hibernate in near freezing water temperatures.

The system I started up in the summer of 2012 used mainly Brown Bullhead catfish since fingerling sized fish are easily caught throughout the northeast and the fish are notorious for their hardiness. This makes them very forgiving when conditions in the system go to extremes compared to other fish. Ironically, one of the other fish I have found to be almost bulletproof when it comes to water conditions are goldfish and more recently Yellow Perch.

When I originally started researching aquaponics in the summer of 2011, I really wanted to try the system with Channel Catfish but the two batches of fish I got from local pet stores were killed off by ich (protozoan parasite) as there was no way for me to treat them outdoors.

Last summer, I decided to try the Channel catfish again, but this time using an indoor aquarium type system to grow them to a size suitable for putting outdoors this spring. My first batch died when a power strip tripped and I lost filtration and aeration. So I bought another batch this past fall and started over again. Fortunately, I have made it to this point, and barring any other problems I'm going to put them outdoors in the next month or so.

I would like to go over some basic principles first. Let's start with a simple scenario where we have a bucket filled with water and some fish.



Fish, like many other animals, produce waste that they must excrete or rid from their body in some way. The most toxic and abundant of these wastes is ammonia, NH[SUB]3


[/SUB][SUB]I will discuss the source of the ammonia later. To lessen the toxicity of ammonia, many animals combine ammonia, with carbon dioxide using the Urea Cycle:

[/SUB][SUB]

No, you don't have to memorize the above. This conversion does require energy on the part of the animal. The overall equation is as follows:

2NH[SUB]3[/SUB] + CO[SUB]2[/SUB] -----------------→ CO(NH[SUB]2[/SUB])[SUB]2[/SUB] + H[SUB]2[/SUB]O
ammonia + carbon dioxide ----→ urea + water

Urea molecule:



Why do animals convert ammonia (NH[SUB]3[/SUB]) into urea? Urea is much less toxic than ammonia, so it is a way for the body to transport ammonia through the bloodstream without causing a lot of toxicity. Once the urea reaches the kidneys, the latter filter the urea out of the blood Yes, fish do have kidneys that filter the urea from the blood. The kidney makes urine that travels to the bladder and from there the urea-containing urine is expelled into the surrounding water. If you've ever gutted a fish, you may have noticed the urinary bladder (as opposed to the air-filled swim bladder). During the stress of being on a hook, the fish often expels all the urine so it may not be full and therefore more difficult to see.

There is another method by which fish get rid of ammonia. Instead of combining it with carbon dioxide (CO[SUB]2[/SUB]) to make urea which then goes out through the bladder, ammonia can get expelled directly from the bloodstream into the surrounding water by diffusing across the fish's gills. The advantage of this method is the fish does not expend any energy as the ammonia crosses from the fish into the water as the concentration is higher in the blood than in the water around the fish.

Now back to our container of fish . . .
[/SUB][SUB]
As the fish produce ammonia and urea waste, the concentration of these products begin to increase in the surrounding water. If fresh water is used to replace the ammonia and urea-laden water, then the ammonia never reaches a toxic concentration. Ideally, there should be zero ammonia as even small amounts can affect the fish's health. But if the amount of water exchanged keeps the ammonia levels low, the fish will remain healthy. If, however, the ammonia is allowed to build up, then eventually it will reach a lethal concentration. The fish are literally bathing in their own waste. Not to be graphic, but this would be like drinking your own urine instead of fresh, clean water. Interestingly, the fish will all die within about 24 hours of each other, that is how predictable lethal ammonia levels are.

A quick point about urea: Many bacteria have the enzyme urease which breaks urea back down into ammonia and carbon dioxide. Because of this, urea in a container of fish will get broken back down into ammonia. If you've ever left a toilet bowl full of urine overnight, this is the reason the toilet smells strongly of ammonia. Your bladder (and likely the toilet bowl) contain bacteria that will break urea back into ammonia, giving off that strong smell.

To summarize:

1) Fish produce ammonia as waste.

2) Ammonia is very toxic and is disposed of by the fish in the surrounding water.

3) If the ammonia is not removed from the water, the fish will eventually die.

Pretty simple so far. I will either edit this post or add another one. More to come.[/SUB]

 

[Mr. Brownstone]

Subbed. Great stuff! Thanks, C-4.

 

[stixnstones]

Interesting reading. I like the idea of using native species when you can. Have you figured out the cost per pound of meat?

 

[C-4]

[SUB]

Interesting reading. I like the idea of using native species when you can. Have you figured out the cost per pound of meat?

No, I started out to but it's tough to do all the measuring. I will do it with the Channel catfish. I'm keeping them separate from the other species. It will be more clear later how I'm doing it. Technically, even the Channel catfish is a native species to New Hampshire since the Connecticut River has some. derek has fished for them. Up where I am we don't have any (Central NH Lakes Region).

To recap, the first principle of aquaponics is understanding that fish produce waste, mainly ammonia, that will increase in concentration until it reaches a lethal level. Even when fish are starved, they continue to metabolize fat and muscle and therefore produce waste. Almost all of the ammonia waste comes from metabolizing muscle. I will bring this point up again at a later date. One way to remove ammonia is through water changes. This consists of removing a certain % of water from the container and replacing it with fresh, ammonia-free water. If I wanted to maintain a container of fish, I could simply do water changes daily to every few days, and not have any kind of filtration system of any kind. The fish below are my Channel catfish (there are two fish that are Brown Bullhead catfish in the picture) currently kept inside in a 75 gallon stock tank. I could remove, say, 15 gallons or 20% of the water every day or every other day, replace it with fresh water, and that should keep the ammonia levels low enough for the fish to remain healthy. This is a time-consuming and water wasteful (not that we don't have enough water in the northeast to do this).



In fact, many fish farms use exactly this method: Water is drawn from a stream or well, and fed into a container of fish, often a concrete tank, and the polluted water is allowed to overflow, with some kind of netting or obstruction not allowing the fish to escape. Alternatively, a constant flow system allow water to flow through continuously, and this carries away all the fish waste. This is used mostly in the aquaculture of trout where concrete raceways are used to contain the fish.





The concrete container can take on many shapes. Here is one that is cylindrical.


[/SUB]
[SUB] Such a system is effective when there is essentially an unlimited source of renewable water. However, it falls into the category of aquaculture and not aquaponics since the water is not contained and the ammonia and other wastes used to fertilize plants (more on that later). I am posting the information to illustrate how fish can be grown and kept healthy as long as they are not bathing in their own wastes. How the water is kept clean is mostly irrelevant to the fish.

My biological filtration system is not set up yet outdoors but I do have some Brown Bullhead catfish, Yellow Perch and goldfish that I already have in the outdoor 550 gallon fish tank. For now, I am using water exchanges to keep the ammonia levels down.

Filling the 550 gallon fish tank. My hose puts out about 5 gallons of water a minute so it takes about 110 minutes to fill the fish tank.



Side view of 550 gallon fish tank.



Top view of fish tank. Here it is easy to see that the 2" stand pipe extends from about 3" of the bottom of the fish tank all the way to a T-junction. The latter is open at the top and another pipe comes off laterally, through the side wall of the fish tank, and flows onto gravel on the ground. This is temporary until the biological filtration is set up.



Here is a close-up of the top of the stand pipe. The reason for the open top is to allow water to escape into it if the bottom inflow is blocked by fish or debris. In a scenario where the bottom of the standpipe is blocked, the water will rise to the point where the water level is above the open top of the standpipe and therefore can flow into it. The water then continues out the side of the standpipe. There is a 1/2" plastic mesh screen at the bottom of the standpipe secured with some zip-ties so most everything can get through. Fish waste is smaller than 1/2". About the only thing that could block it is a dead fish.



This is the in-flow from the hose. The clean water comes in the top, and the ammonia-laden water comes out from the bottom of the fish tank up through the stand pipe and out the side.



In my next post, I will cover the Nitrogen Cycle which describes the creation, processing and destruction of ammonia. Once we've gone over that, we can then move on to how it relates to the closed aquaponics system.

[/SUB]

 

[coastie]

This is awesome. Thank you.

 

[Prepper]

I'm not sure I would like to eat catfish, but I was wondering if there were a way I could raise tilapia. Obviously they would never survive the winter if done outside. But, I don't have room in the main part of the house for large tanks. I have the basement (which reaches 45F in the winter), and the unheated garage. Is heating the water viable to deal with the cold? Also, I was wondering if fish could be raised fast enough to do outside before winter comes and they all freeze.... E.g. start in spring in outdoor pond, harvest before they freeze. I'm guessing not feasible since I have never heard this done this far north, but I am not certain.

 

[Twigg]

Catfish is great eatin' ! I wish I had the room to do this.

 

[454]

Awesome info! I've been looking into starting one of these, but 1 big project at a time for me and this summer its the chickens. I do know a decent amount about fish care from having smaller tanks since I was little but nothing of this size/scale so I'm definitely interested in your experiences, thanks for coming over to share! Great idea on the catfish, I looove catfish and I think the prospect of using them over tilapia or goldfish just moved it up on my to-do list. Have you gone a season using the waste water to feed a garden? If so, what grew well and what didn't? I've read its best for basils, lettuces and other plants that don't require a bunch of different nutrients and that are primarily nitrogen feeders, did your experience align with this?
Prepper, depending on the size of your tank, you could get a stock tank de-icer/heater to keep the water from freezing, the kind horse people use for their stock tanks in the winter. You could also get a programmable heater for large fish tanks to keep it at a set temperature other than just above freezing.

 

[Kevin_NH]

Is it possible to go to big, end up with water that doesn't have sufficient nutrients to actually do any good for the plant side of aquaculture? I ask because I'm thinking about a +1000 gallon in-ground pond, deep enough that I don't have to worry about it freezing solid in the winter.

I'm not sure I would like to eat catfish, but I was wondering if there were a way I could raise tilapia. Obviously they would never survive the winter if done outside. But, I don't have room in the main part of the house for large tanks. I have the basement (which reaches 45F in the winter), and the unheated garage. Is heating the water viable to deal with the cold?

Catfish should survive a constant 45F nicely, but won't put on weight at that temperature. They would probably do okay in the garage with just a circulating pump.

Heating the water could get very expensive. Most people just use a small "stock tank" heater, it just prevents the tank from completely icing over, allows some gas exchange to atmosphere.

 

[C-4]

I'm not sure I would like to eat catfish, but I was wondering if there were a way I could raise tilapia. Obviously they would never survive the winter if done outside. But, I don't have room in the main part of the house for large tanks. I have the basement (which reaches 45F in the winter), and the unheated garage. Is heating the water viable to deal with the cold? Also, I was wondering if fish could be raised fast enough to do outside before winter comes and they all freeze.... E.g. start in spring in outdoor pond, harvest before they freeze. I'm guessing not feasible since I have never heard this done this far north, but I am not certain.

Even in the spring, summer and fall, you need supplemental heating for tilapia. There are people that have done it in greenhouses so it certainly can be done. But tilapia grow between 75 to 85F, stop growing when the temperature reaches 70F and die when it drops to 50F. There is no way getting around those numbers. With supplemental heating, in a greenhouse, you could probably grow from March until October, so 8 months. In that time, you could easily get edible sized fish. But you must heat.

ETA: Grow Yellow Perch instead. Most people like the taste and none of the temperature worries. I'm going to try them again this year and get them on pellets hopefully.

 

[C-4]

Awesome info! I've been looking into starting one of these, but 1 big project at a time for me and this summer its the chickens. I do know a decent amount about fish care from having smaller tanks since I was little but nothing of this size/scale so I'm definitely interested in your experiences, thanks for coming over to share! Great idea on the catfish, I looove catfish and I think the prospect of using them over tilapia or goldfish just moved it up on my to-do list. Have you gone a season using the waste water to feed a garden? If so, what grew well and what didn't? I've read its best for basils, lettuces and other plants that don't require a bunch of different nutrients and that are primarily nitrogen feeders, did your experience align with this?
Prepper, depending on the size of your tank, you could get a stock tank de-icer/heater to keep the water from freezing, the kind horse people use for their stock tanks in the winter. You could also get a programmable heater for large fish tanks to keep it at a set temperature other than just above freezing.

Green leafy veggies do very well. One of the things that seems to grow very well for me is horseradish. But they don't always form a root and sometimes simply make a big "hair ball" of roots. This year I am concentrating on getting enough plants into the system to remove all the nitrogen waste and not have to do water changes. So, technically, there would be no waste water since no water would be removed from the system to water the soil garden. I did use the waste water last summer to feed potted pepper plants next to the aquaponics system and they did well.

 

[C-4]

Is it possible to go to big, end up with water that doesn't have sufficient nutrients to actually do any good for the plant side of aquaculture? I ask because I'm thinking about a +1000 gallon in-ground pond, deep enough that I don't have to worry about it freezing solid in the winter.


Catfish should survive a constant 45F nicely, but won't put on weight at that temperature. They would probably do okay in the garage with just a circulating pump.

Heating the water could get very expensive. Most people just use a small "stock tank" heater, it just prevents the tank from completely icing over, allows some gas exchange to atmosphere.

An in-ground pool is a good idea as it's naturally insulated. In fact, you could figure out an insulating system above it plus a heater to keep the water just above freezing.

As far as nutrients, if there aren't enough in the water, keep adding fish. The truth is most people have a problem with too much nitrogen and other nutrients in the water rather than too little. They stock the tank heavily with fish and the plants can't keep up with removing it. Trust me, you'll have no problem getting enough fish waste into the water.

As far as catfish surviving: Two winters ago they did extremely well with zero mortality. This last winter they didn't fare so well. The difference was that the winter was so brutally cold that I had a hard time doing enough water changes to keep the ammonia levels down. Bacterial infection took over many of the stressed fish and I lost a lot of fish. I kept them in a 100 gallon stock tank in the garage with a water circulator. I had to use some supplemental heat with a kerosene tower heater because of how cold it was this winter even inside the attached garage. I could have easily done it with a small heater inside the tank which works just as well.

If you or someone else wants advice on keeping the fish inside a garage, I have two winters under my belt so far, or 3 if you count the previous year where I kept two large goldfish and 3 hornpout. No mortalities that very first year (3 years ago).

 

[coastie]

Do you have any idea what it costs you per lb of fish harvested? What about crayfish? I saw on the arf posts that you were messing with them. I might try to fool with them as a way to use the scraps from my quail processing as feed.

 

[C-4]

Do you have any idea what it costs you per lb of fish harvested? What about crayfish? I saw on the arf posts that you were messing with them. I might try to fool with them as a way to use the scraps from my quail processing as feed.

I don't have those kinds of numbers but plan on doing some calculations with the Channel catfish. Ironically, the cost of feed in commercial aquaculture operations where catfish are raised in ponds comprises about 50% of the budget. In an aquaponics system, most of the cost is the actual equipment depending on what you are using. For instance, if you go with a commercial grow bed specifically designed for aquaponics, it will run you into the hundreds of dollars. If, on the other hand, you use a series of 55 gallon plastic drums cut in half, those can be sourced for free plus the labor in cutting it in half with a Sawzall. Or if you get used food grade 275 gallon totes, those can be had on Craigslist for very little. I've looked into the 275 gallon totes and I've found them around here locally so I don't imagine it would be difficult to find in most places. The only stipulation is to make sure they are food-grade and never held anything toxic to fish. Something like a syrup or other benign liquid is easy enough to clean out. A submersible pond pump you find at Home Depot or Lowes is more than adequate, and because they are meant for ponds, they contain no oils and are fish-safe. The grow bed material I'm using this year is expanded shale. I would find out how much you can get it for locally and what sizes they carry. If they already have some of adequate particle size and you have a truck to transport it in, you can get that for relatively little. All the piping and tubing can also be sourced at Lowes or Home Depot.

The feed is going to be the least expensive aspect but if you are coming up with your own then that is going to be less of an issue.

 

[C-4]

I haven't forgotten about this. Since I'm using a new grow bed for the plants using expanded shale instead of gravel, and since I am going to use Channel catfish in addition to Brown Bullhead catfish, I am going to be documenting more information such as fish weight going in, amount and type of feed, water temperature, etc. The Channel catfish are still indoors and the Brown Bullhead catfish are doing well outside with water changes. Just to give a peek, I filled the grow be with the expanded shale today. Don't worry, I will go through the steps very carefully. So far the only thing I've covered is keeping fish in a container with no filtration and how the ammonia level goes up in the water. That's going to be my starting point for the next step. I'm probably going to end up doing this real time, as in I will post as I go to the next step and describe in detail what is happening in the system and why it is important.

I should have made this more clear in the beginning: My goal here is to describe what is happening so you will understand the basic concepts ie. the principles of aquaponics rather than a how-to in terms of the actual plumbing of aquaponics. This isn't a cook book but rather making sure you understand what is happening so you can reproduce it on your own. People here who keep aquariums already understand the principles, but this will be a good refresher for them.

I will get to the grow bed principles in the very near future. I filled the grow bed today with expanded shale. The grow bed is approximately 48" wide X 80" long X 15" deep. This translates into approximately 250 gallons of expanded shale. More later.

 

[xcom]

This is great. We had just hydroponics and had tree cut downand the guys knocked out the power cord. We came home from vacation and everything was dying. Moral of the story: power backup or solar....

 

[enbloc]

.

 

[C-4]

Thanks, guys. In case someone is wondering, the reason to have the tarp covering the fish tank is to prevent algae from growing. You have nutrient rich water + sunlight = algae bloom. As long as you limit light, you will have very little if any algae growing in your system. The water level in the grow bed stays about 1" below the top of the expanded shale so the water doesn't get enough sunlight to grow anything.

 

[headednorth]

Very cool stuff, thanks. Sub'd.

 

[Finalygotabeltfed]

Where's the veggies?

 

[C-4]

Where's the veggies?

Patience, my friend. We'll get into cycling the system to grow bacteria. During this period, many people will not put plants in since you get big spikes in nitrite which can be toxic to plants. I've also read that the risks are overstated since plants can process nitrite to some extent. My plan this year is to maximize the growth of the best plant for my system so as to absorb as much nitrate as possible. That happens to be horseradish for my system. It has grown extremely well in the last two years for me. I will likely plant some cucumbers as well. Here is a picture of the horseradish that I've started indoors. I saved the entire root of one plant from the aquaponics system last year in a ziplock bag in the refrigerator. I cut inch-long pieces for planting. The leaves have grown out much more so. I will wash off the peat/soil before planting it in the expanded shale.

 

[C-4]

Update: 05/23/2014 Ammonia processing by bacteria

So far, we've learned that:

1) Fish produce ammonia as waste.

2) Ammonia is very toxic to fish and is disposed of by the fish in the surrounding water, either directly diffusing from the blood through the gills and into the water or through urine (yes, fish do pee and have kidneys and a bladder!).

3) If the ammonia is not removed from the water, the fish will eventually die due to toxic levels of ammonia.

So how is the ammonia removed from the water? Ammonia can leave the water in two ways:

1) It can be absorbed directly by a living organism. For instance, in the natural environment, plants and photosynthetic bacteria can absorb ammonia directly through their roots or cell membranes respectivesly. For many cyanobacteria (bacteria that derive their energy from photosynthesis), ammonia is actually the preferred nitrogen source. Most plants prefer to absorb nitrate, but they also have transportation mechanisms in their roots that can directly absorb ammonia.

2) It can be transformed by bacteria into other, much less toxic compounds. Specifically, ammonia oxidized by certain bacterial species into the nitrite ion, and then other bacterial species convert the nitrite ion into the nitrate ion.

Mechanism #1 is self-explanatory. Plants and certain bacteria can simply absorb ammonia directly from the water, thereby preventing toxic levels from being reached. Plants and bacteria are happy. Fish are happy.

For mechanism #2, there are two specific bacterial species in freshwater that concern us: Nitrosomonas and Nitrobacter.

1) Nitrosomonas: This bacteria specifically oxidized ammonia to the nitrite ion. To illustrate what is happening, I'm going to use a more familiar reaction, that of the oxidation of methane.

Methane is a carbon atom surrounded by hydrogen (CH[SUB]4[/SUB]). It is analogous to ammonia which is nitrogen surrounded by hydrogen atoms (NH[SUB]3[/SUB]). Let's use the reaction of methane with oxygen but oxidize the methane to carbon monoxide (CO):

2CH[SUB]4[/SUB] + 3O[SUB]2[/SUB] -------> 2CO + 2H[SUB]2[/SUB]O

In the above reaction, oxygen combines chemically with the carbon portion of methane as well as with the hydrogen portion producing carbon monoxide (CO) and water (H[SUB]2[/SUB]O) respectively. We say in this case that carbon is oxidized. This of course requires a rich source of oxygen or the reaction cannot take place.

In the same way, ammonia can be oxidized by oxygen inside the Nitrosomonas bacteria and leads to an oxidized product of nitrogen, in this case it leads to nitrite. The analogy isn't perfect since nitrite is actually an ion with a negative charge but the general principle of oxidation is the same. The unbalanced equation is as follows:

NH[SUB]3[/SUB] + O[SUB]2[/SUB] ----------> N0[SUB]2[/SUB]- + H[SUB]2[/SUB]O

Why would a bacteria want to oxidize ammonia in the first place? What benefit does it get from doing so? In the process of oxidation, energy is released, in the same way we derive energy from oxidizing methane (natural gas) for cooking our food and heating our homes. In the case of ammonia oxidation, the bacteria will use that energy to run all other reactions inside the bacteria. So the Nitrosomonas bacterial species uses ammonia as an energy source just like humans use sugar/carbohydrates. They oxidize ammonia and we oxidize carbohydrates. Keep in mind that both the bacteria and humans need a plentiful supply of oxygen to accomplish this task. This is an important principle that I will touch on later.


2) Nitrobacter:

However, nitrite is not a harmless chemical to fish. In fact, it is far more toxic to fish than ammonia is! But nitrite doesn't stay for long as there is a second bacterial species, Nitrobacter, that actually feeds on nitrite, oxidizing it further to the relatively harmless nitrate. The analogy to methane holds as now you have oxidation of carbon monoxide (relatively toxic) to carbon dioxide (relatively harmless). While carbon dioxide is not completely harmless to humans, we can tolerate a certain amount of it in our blood. Carbon monoxide, however, is extremely toxic to humans in even low concentrations. The formulas look something like this:

2CH[SUB]4[/SUB] + 3O[SUB]2[/SUB] -------> 2CO + 2H[SUB]2[/SUB]O

The next step is oxidation of the carbon monoxide to carbon dioxide:

2CO + O[SUB]2[/SUB] -------> 2CO[SUB]2[/SUB]

In the same way, Nitrobacter takes nitrite and oxidizes it with oxygen to nitrate:

2NO[SUB]2[/SUB]- + O[SUB]2[/SUB] ----------> 2N0[SUB]3[/SUB]-

Why would a bacteria want to oxidize nitrite in the first place? What benefit does it get from doing so? In the process of oxidation, energy is released. Nitrobacter species of bacteria use the oxidation of nitrite to nitrate to run all other reactions inside the bacteria. So the Nitrobacter bacterial species use nitrite as an energy source just like humans use sugar/carbohydrates. They oxidize nitrite and we oxidize carbohydrates. Keep in mind that both the bacteria and humans need a plentiful supply of oxygen to accomplish this task. This is an important principle that I will touch on later.

To recap:

1) We understand that fish produce ammonia as a by-product of their metabolism and they dispose of it in the surrounding water.

2) If ammonia rises to toxic levels, it will kill the fish.

3) There are two bacterial species, Nitrosomonas and Nitrobacter, that use ammonia and nitrite as a 'food' source respectively, leading to the chemical transformation of the relatively toxic ammonia, to the even more toxic nitrite, and finally to the relatively harmless nitrate.

But how do we process the water to maximize its exposure to these two bacteria, thereby turning all the ammonia into nitrate? This is conceptually much simpler that it would seem. For those of you who keep aquariums, this is old news. Both Nitrosomonas and Nitrobacter species can grow on surfaces. In the aquarium setting, they will colonize gravel at the bottom of the aquarium or any other surface. To take advantage of this, the filtration system of the aquarium contains a substrate onto which the bacteria will attach and grow. Most of these are made from ceramic beads or cylinders, fired clay, or plastic. Plastic sponges are often used as well, sometimes in combination with ceramic beads or tubes.

I cleaned out my indoor filter to both illustrate the concept and also to 'harvest' bacteria for my outdoor aquaponics system. The 'aquarium' is actually a 75 gallon stock tank used normally as a water source for farm animals. I currently have Channel catfish in it that I will be putting into my outdoor aquaponics system.

I use a canister filter which houses the substrate onto which the bacteria grow. To give you an idea of how these look, I found this picture on the internet that shows a canister filter with a clear housing:

1) The top of the canister contains a small pump that creates the water flow. Water is drawn in through a tube at the bottom of the canister.

2) It then travels through a plastic sponge or fibrous material similar to cotton but made from a synthetic polymer. This traps solid waste from the fish. The fish waste, though, continues to be processed by many different bacterial species so that it keeps getting broken down. If it didn't get broken down/eaten by bacteria, the filter would quickly get clogged.

3) The ammonia-containing water continues up the canister through ceramic beads or other materials. It is in these locations that the Nitrosomonas and Nitrobacter species are present in their highest concentrations. It is here that the process of chemically converting ammonia into nitrite and then into nitrate takes place the most. A great analogy of what takes place here is similar to what happens in a car's catalytic converter. In a catalytic converter, ceramic beads or similar materials are covered in various catalysts. These break down more harmful chemicals into less harmful or harmless ones. For example, carbon monoxide is converted by platinum and paladium into carbon dioxide, thereby decreasing the amount of carbon monoxide in the vehicle's exhaust. Here it is illustrated:

In the case of our bacteria, the 'catalyst' that helps converts ammonia to nitrite is an enzyme called Ammonia Monooxygenase, and is present in Nitrosomonas bacteria. The enzyme present in Nitrobacter bacteria that converts nitrite to nitrate is called Nitrite Oxidoreductase. Enzymes are biological catalysts. In the same way as palladium above helps the conversion of carbon monoxide to carbon dioxide, the aforementioned enzymes help the bacteria with the conversion of ammonia to nitrate.

I like this analogy because it illustrates how water flows over the bacteria and the ammonia is converted to nitrate. So the canister 'filter', while filtering some solid fish waste, also acts in a catalytic way, converting harmful chemicals into less harmful ones.

4) The detoxified water is then forced out the top of the canister where it returns back to the fish tank or aquarium.

Today, I went ahead and cleaned out my canister filter for the purpose of collecting bacteria to add to my outdoor aquaponics system.

This is the outflow from the fish tank shown earlier. Water exits the tank here.

The water flows through tubing in this picture from right to left until it reaches the bottom of the canister filter.

Once it has passed through all the layers of the filter, it returns back into the fish tank via a multi-perforated tube to maximize the amount of oxygen added to the water. Remember that the processes in the canister filter require well oxygenated water as the bacteria use that oxygen for their conversion reactions.

The first thing that I do is shut the valves in the tubing. This prevents air from entering the tubes and causing too much air to enter the system. This can cause the pump in the canister to fail when it is reconnected with the tubing.

Next, the top is removed. This top houses the small pump that drives the water through the canister.

There is a spacer that is removed, then a blue plastic sponge.

This sponge is cleaned under running water to remove any insoluble fish waste and also Nitrosomonas and Nitrobact bacteria.

The plastic filter floss material is removed next and rinsed.

These are two plastic mesh bags that are filled with ceramic tubes covered in bacteria. This is where all the ammonia detoxification takes place along with other bags I will show below. The ceramic is rinsed of any fish waste and some bacteria will to with it.

These are charcoal filters. They can remove some toxins that build up. They are not important as far as I am concerned in the absorption of ammonia. Honestly, I personally do not think they are necessary, but the Canister Filter gods require them so I put them in there.

The following are two more mesh bags but this time filled with spherical ceramic beads. I don't think you can have too much filtration so that's why I added them. I also have a lot of fish in there so I think I need them.

Close-up.

Next is more filter floss. You can see how brown the rinse water is in the 5 gallon bucket to the right!

Another blue sponge filter.

Rinsed.

Lastly is another space.

This is a separate 5 gallon bucket with the contents of the canister filter all stacked up. This was returned to the canister and I reconnected it with the fish tank.

This is 5 gallons of fish waste with a high concentration of both Nitrosomonas and Nitrobacter species of bacteria. This is some high-priced bacteria that is critical for my aquaponics system. I have a friend that gave me some sponges from his 90 gallon aquarium along with all the washings from his filter. As I'll note below, I am using it to populate my outdoor aquaponics system.

 

[C-4]

The next step is setting up the outdoor aquaponics filtration system. The principles are going to be identical to the canister filter in terms of water flowing through a bacteria-covered media, though the set-up will be different because we are partially using gravity to accomplish the task. But first, let's re-cap.

So far, we've learned that:

1) Fish produce ammonia as waste.

2) Ammonia is very toxic to fish and is disposed of by the fish in the surrounding water, either directly diffusing from the blood through the gills and into the water or through urine.

3) If the ammonia is not removed from the water, the fish will eventually die due to toxic levels of ammonia.

4) The removal of ammonia can be done directly by plants, and can also be done by beneficial bacteria that process relatively toxic ammonia to relatively harmless nitrate.

5) This process needs to take place in such a way as to expose the water to the maximum surface area of bacteria. This is accomplished by having the water flow through a bacteria-covered medium. In the canister filter example above, that medium is ceramic beads and short tubes. In my aquaponics system, I will be using expanded shale, a natural clay that is mined and then fired at high temperature to create a light-weight, porous material perfectly suitable for bacteria to grow on.

The new grow bed uses the sump tank from last year. I've raised it on 6 pillars made from 6 cinder blocks. The cinder blocks were arranged 2 side by side with 2 placed side by side at a 90 degree angle from the first two, then the last 2 placed side by side at a 90 degree angle from the middle two blocks. I had help with the 3/4" treated plywood boards. I have a guy who does other work for me bring them by and he cut off the ends so it was 80 inches long (6'8") and 4' wide. This is the approximate dimension of the bottom of the sump tank. I put two layers of the plywood which comes to approximately 1 1/2". The cinder blocks 3 tall comes to 23" so the grow bed is 24 1/2" off the ground/gravel.

Empty grow bed in the middle set up on cinder blocks and pressure-treated plywood:


Other angles:

Using a hole saw, I drilled through the plastic bottom of the grow bed and through the plywood. I then used the hole saw bit to enlarge the wood portion so I could put a Uniseal flexible tank/bulkhead adapter.

The plywood looks like it is more than 3/4".

Since I'm using a 2" PVC pipe for the drain, I have a 2" Uniseal adapter. The actual hole I drilled is 3" in diameter as it needs to be a bit bigger to accommodate the Uniseal.

The 2" PVC stand pipe is then inserted into the Uniseal adapter. Make sure you wet it first or you will have a hard time getting it into the hole. This is another reason why the wood below has to be cut even larger so it doesn't impede the passage of the pipe. You can use saliva to lubricate. I wanted to avoid using dish soap but a small amount will wash away and shouldn't affect the fish at all.

The attachment is a little more complicated. Here you see the stand pipe below the grow bed. I didn't want to glue everything in place because you can only use a saw to take it apart, but I also recognize that over time the hand-fit pieces will work loose. So what I did was put a few layers of teflon tape around the male end of the PVC pipe, then inserted this into the 90-degree angle PVC, then put some duct tape over that. It's not going anywhere, but it also allows me to change things around easily instead of having to cut glued pieces off with a PVC saw. The last two years I didn't even use teflon or duct tape but just hand-fit the PVC pieces.

I then put a wood dowel under the 90 degree angle PVC connection so it further ensures that it says in place.

Next I added a length of PVC with teflon/tape to keep in place, and ran it through a 3" hole in the sump tank:

The set-up of the automatic bell siphon (I will discuss the automatic bell siphon below in more detail) isn't complete until the gravel/expanded shale 'guard' is pot around the stand pipe. This is to help prevent gravel, expanded shale or grow bed material from escaping out of the grow bed into the sump tank. I re-used the same blue bucket from last year that has 3" holes drilled into it, but I changed the screen to a much finer mesh one because there is quite a bit of finer material in the expanded shale that I bought. IIRC, it is 3/8" material but there is a lot of finer material in there. I don't really care as the bacteria don't care. But, I did have to put a smaller mesh around the blue bucket to prevent all that finer material from ending up in the sump tank.

Close-up of the finer mesh used around the gravel guard which is placed around the automatic bell siphon set-up. Here we only see the stand pipe. The bell portion goes over this.

Finer mesh. Last year I used 1/2" mesh:

It's important to keep as much metal out of contact with water in your system as possible. Plastic in the form of PVC, synthetic rubber, etc is not going to be affected by the water, and it won't rust or leach metal into the water. Some metal is unavoidable, but you can almost always find a non-metal/plastic alternative. Plastic zip ties are used throughout. This fine mesh screen is made, IIRC, of a PVC coated fiberglass. Most of the materials you'll need are available locally at Lowe's, Home Depot, etc.

This is a great picture showing the grow bed with the stand pipe, gravel guard (ETA: this is the old one with the larger mesh size) and the pipe going into the sump tank. I like having a lot of pictures so people can see all the perspectives and hopefully understand this well:

That covers the outflow of the system. As far as the inflow, I wanted to put in a pipe, maybe 7 or 8" in diameter that would go straight to the bottom of the grow bed, and into which the water will flow in from the fish tank. This is not going to happen until the system is fully cycled, but I still wanted it all in place for when I did this. I couldn't find exactly what I wanted, and I didn't want to use another 5 gallon bucket as it does take up more space in the grow bed than I wanted it to. So I went to the hardware store and found some plastic end connectors and put them together into what I wanted:

3" holes drilled to allow flow out of the pipe:

Connecting the pieces was easy by punching holes and connecting the 3 pieces with plastic zip ties:

Inside view before trimming the zip ties:

Zip ties trimmed:

Since I didn't want expanded shale pouring into the holes

, I put 1/2" plastic screen around my pipe. Again, zip ties were used to secure it in place:

Since I had already filled the grow bed, I had to dig out some expanded shale and put in the pipe. This is what the water from the fish tank will flow into. It will give a place for the water to go and avoid a lot of splashing onto the leaves which can cause fungal and other diseases to flourish. You can see the hole where the pipe from the fish tank will come in:

As noted, I am using expanded shale for the grow bed instead of gravel.

I put the stand pipe at 15", so the dimensions of the grow bed are 80 inches long X 48" wide X 15" deep. This gives 57,600 cubic inches or 249.35 gallons. I'm rounding it off to 250 gallons since the bed is slightly tapered going up, so there is likely several more gallons, maybe even up to 10 gallons or more of space in there. I'll use 250 gallons as a nice round numbers. This is 946 liters in case you were wondering. The volume of grow bed material is a critical numbers since it tells us how much material there is for bacteria to grow on, and therefore how much bacteria we have available for processing ammonia and other fish waste. The shale was just shy of the 15" needed so I did fill a 10 lb onion bag with 3/8" gravel and buried it under the shale in one corner so I could raise the expanded shale a little more. Ideally, you want at least 1 to 2" of grow bed material above the water line ie. the top of the stand pipe so everything stays dry on the surface of the grow bed. Why? Because this prevents fungal and other diseases from affecting the plants and it also prevents algae from growing on the surface of the grow bed material. I could have just lowered the stand pipe to 14", but I want to maximize the grow bed volume and get as much bacteria in it as possible.

I chose not to rinse off the expanded shale before putting it into the system and instead flood and drain the system with water to rinse it. It was a lot easier to do it this way, but when I put the bad of gravel in there, it did disturb the shale enough that the water is not crystal clear. This isn't a big deal now because I have no fish in the system and I'm simply cycling it for bacterial growth. I will do a water change again before adding fish and it will be crystal clear. You really want to be able to see the fish well so inspect for disease, dead fish, uneaten food, etc. The expanded shale is much less dense than gravel. It also has more surface area so I will be interested in seeing how well bacteria grow on it.

Now for the food the bacteria are going to eat. I've chosen to cycle the system with urea:

Many bacteria have the enzyme urease which breaks urea down into ammonia (NH[SUB]3[/SUB]) and carbon dioxide. While the two that we are concerned with, Nitrosomonas and Nitrobacter, may not have strains that will all do this, the seeding bacteria I am using for my system likely contains dozens of species of bacteria so I'm not worried the urea won't be broken down into ammonia.

So any urea that goes into the system is quickly converted to ammonia which is the actual food that the bacteria will eat. It's simply much easier to measure out urea than liquid ammonia. Any source of ammonia is fine. You could use ammonium sulfate, ammonium chloride or ammonium phosphate. I happen to have ammonium sulfate (this as well as aluminum sulfate are used to acidify the soil for my blueberries). You could even use ammonium nitrate, but I would not do this since you won't be able to see if your system is starting to produce nitrate as it will already be in your system! Some even urinate into the system as there is 9 grams of urea per liter of urine. While there is absolutely nothing wrong with doing this, and the system will cycle just fine with any source of ammonia, I have no desire to do this.

Most aquarium hobbyists use between 4 and 8 ppm (parts per million) of ammonia to cycle their aquariums. [span style='text-decoration: underline;'][span style='font-weight: bold;']Remember, this is done without any fish in the system as ammonia is toxic and, as we'll go over later, the nitrite that is produced as an intermediate product is even more toxic to fish.[/span][/span] I'm going to shoot for 8ppm of ammonia and then check the level. Some of the ammonia may bind to the expanded shale so I may have to dose the system a second time. That's fine since the bacteria are growing on the expanded shale surface.

I grew up in Canada so I like using the metric system for some measurements. The sump tank (which used to be the grow bed the last two years) is 300 gallons total. I don't have an exact measurement, but I would estimate the water level at about 225 gallons. I think this is pretty close. So . . .

225 gallon = 851.7 liters ~ 852 liters

1 ppm of a liter is 1mg so we need 852 liters X 1mg/liter = 852 mg for 1ppm in the 225 gallons of water.

But since we are shooting for 8 ppm, we will multiply 852 mg X 8 = 6816 mg = 6.816 grams ~ 6.8 grams. That will give us 8 ppm of NH[SUB]3[/SUB].

However, we're not using ammonia, we're using urea. For each molecule of urea hydrolyzed by , we produce two molecules of ammonia when it is broken down by bacteria:

CO(NH[SUB]2[/SUB])[SUB]2[/SUB] + H[SUB]2[/SUB]O -------------> 2NH[SUB]3[/SUB] + CO[SUB]2[/SUB]

We want 6.8 grams of ammonia (NH[SUB]3[/SUB]). Since the molecular weight of NH[SUB]3[/SUB] is 17 grams/mole, the amount of ammonia we need is 6.8 grams/17grams/mole = 0.4 moles.

Since the molar ratio in the above formula is urea:ammonia = 1:2 we will need only half the number of moles of urea so 0.2 moles. The molecular weight of urea is 60 grams/mole. So we will need 0.2 moles X 60 grams/mole = 12 grams of urea dissolved in 225 gallons of water to obtain a concentration of 8 ppm (8 parts per million).

Why not more ammonia? There is likely a concentration that is optimal for bacterial growth and it likely lies somewhere in the 4 to 8 ppm range. This seems to be empirically derived from aquarium hobbyists and takes into account the generally warmer water used as well as pH optimized for fish-keeping. From all the reading I've done, I think that you can use higher concentrations but you need to be careful because the nitrite that is formed when ammonia is oxidized is going to be toxic to the ammonia metabolizing bacteria (Nitrosomonas). Though you should have Nitrobacter growing as well which will convert the toxic nitrite into the relatively harmless nitrate. I would recommend keeping the initial ammonia concentration below 10 ppm. However, if anyone here has evidence that higher concentrations of ammonia will cycle the system faster then I would gladly like to see it.

So I added 12 grams of urea to the system.

What next? Well, I will measure the ammonia concentration in a few days. I would like it above 5 ppm. If a lot of the ammonia is bound to the expanded shale and the concentration is below that, I will simply add more urea. Then I will measure nitrite levels every few days to see if the bacteria are converting ammonia into nitrite.

The last part of this post will be the final step for the cycling to begin. We have the substrate onto which the bacteria will grow, we have water flowing, and we have food for the bacteria. All we need now is the bacteria! I have 3 small bags of expanded shale in my indoor catfish system but I'm not going to use that yet. I am also planning in the next day or two to clean out my indoor system's canister filter which contains sludge and other bacteria-filled material. So that will all be going into my system in the next day or so. What I put in there today is from my friend who keeps a 90 gallon aquarium. The best source of bacteria for an aquaponics system is either another [span style='text-decoration: underline;'][span style='font-weight: bold;']disease-free[/span][/span] aquaponics system or from the filters of a well-established aquarium. This is loaded with Nitrosomonas and Nitrobacter bacteria that is critical to get the system cycling.

These are two sponges from one of his filter systems. These will go right into the hole where the fish tank would usually empty but where now I have the pump from the sump tank flowing into the grow bed:

Before going into the in-flow pipe, I rinsed the sponges thoroughly in a 5 gallon bucket of water that also had all the rinsed material from my friend's filter.

 

[C-4]

All of that bacteria-laden water was poured into the grow bed and acts as the 'seed' bacteria to eventually populate the entire grow bed expanded shale with nitrifying bacteria. I started cycling the system on 05/11/2014 and on 05/22/2014, 11 days later, I had the following results.

I found only 0.75mg/L (ppm) ammonia. This should be around 8mg/L (ppm) which is the amount of ammonia I put into the system in the form of urea. I can account for some of the ammonia being bound by the expanded shale, but not all 8 ppm.

I did seed the grow bed heavily with Nitrosomonas and Nitrobacter, and I also put about 1/2 gallon of expanded shale from my indoor system into about 250 gallons of expanded shale in the outdoor system. Not much as a percentage, but on day 11 of cycling the system, I had both nitrite 1mg/L (ppm) and . . .

. . . also nitrate at about 37.5mg/L (ppm)[/span]

The only water source for the grow bed/sump tank has been well water which has zero ammonia/nitrite/nitrate and the outdoor fish tank which has about 0.5mg/L of ammonia but zero nitrite and nitrate. I actually checked the outdoor fish tank to make sure I wasn't simply transferring over nitrite and nitrate thus skewing the results. Here is the fish tank nitrite test at zero:

This is extremely exciting for me. The above means that I have a population of both Nitrosomonas and Nitrobacter set up in the expanded shale. It is likely still small, but it means that the potential is there for them to grow. All they need is a source of ammonia and warmer days.

I'm going to check the ammonia, nitrite and nitrate in a couple of days. If the ammonia and nitrite go to zero, then I will do a water change with water from the fish tank to flush out the nitrate, and then I'll replenish the fish tank with well water and connect the system to start the water circulating from the fish tank through the grow bed. Once the ammonia and nitrite drop to zero, the system is said to be "cycled", meaning that there are enough bacteria in the system to prevent a rise in the ammonia levels due to cycling of the water through the system. It's a term you'll read in aquaponics forums and even aquarium forums.

I'm still a little surprised that it has progressed this fast. We have warmer weather in the low 70's coming so this should continue to progress rapidly. This does not mean that I have all the expanded shale covered with bacteria, that would be ridiculous given the relatively low temperatures and short period of time (it can take 6+ weeks to fully cover the grow bed media). It simply means that a population of bacteria large enough to manage the ammonia in the water is present in the grow bed. I will have to be very careful to only very slowly increase the feedings so the fish do not produce too much ammonia to overwhelm the system.

I also have to remember that Nitrosomonas bacteria will grow considerably faster than Nitrobacter bacteria, and that this means there is a 'bottle-neck' between the nitrite to nitrate conversion. This is where people often kill off all their fish in the system. They start feeding the fish like crazy which causes ammonia to rise fast. Nitrosomonas present can handle it, but there is not enough Nitrobacter to take the nitrite and convert it to nitrate. Nitrite concentrations spike and react with hemoglobin in the fish's blood to produce methemoglobin which doesn't carry oxygen. The fish suffocate despite excellent oxygen levels in the water. I killed my Rainbow trout this way IIRC.

The best way to prevent this is to very slowly and very cautiously increase the feeding of the fish, and to also salt the water to 2 or 3 ppt. The chloride ion in salt displaces the nitrite ion from the fish's blood, thereby preventing the formation of methemoglobin.

Once I connect the fish tank to the rest of the system, I'll go over the delicate transition period where the feedings are increased and why it's important to check the ammonia, nitrite and nitrate levels. I'll also discuss diet and it's relationship to ammonia waste at some point. I'll also introduce the plant portion of the aquaponics system. I'll likely be planting the horseradish in the next few days.

There are many more aquaponics principles to go over, but most are fine tuning. There are still a few big subjects that need to be covered.

I will do a quick coverage of the topic of the automatic bell siphon tomorrow. It won't be a long read and in fact I'll refer you to a video as well. It's a very important topic to discuss and you'll see why.

Stay tuned.

 

[Admin]

That is a ton of good information.

 

[C-4]

That is a ton of good information.

Thank you. More updates.

Quick update: 05/26/2014 Nitrites and Nitrates higher!

Day 14

I tested the ammonia, nitrites and nitrates yesterday (05/25/2014) on Day 14 and they were as follows:

The ammonia had dropped slightly from 0.75mg/L (ppm) to 0.5mg/L. Remember, this will have to drop to zero as one criteria for the system to be considered cycled. This is a good sign. It means that a population of Nitrosomonas is well-established. It does not mean that every expanded shale stone in the grow bed is covered in bacteria, far from it. That of course is our end-goal, but it's not necessary for the purpose of connecting the fish tank to the system. All I need is an established population on the shale so I can connect the fish tank to the system. The key here is to prevent ammonia levels from rising too quickly by only slowly increasing the daily feeding of the fish.

The nitrite level is off the chart which means that it is > 5mg/L (ppm). When aquarium or aquaponics hobbyists kill off every last fish, this is often how they do it. Some fish such as tilapia and goldfish can tolerate high ammonia levels for a period of time. But no fish can handle high nitrite levels. It is uniformly lethal. The above ammonia level can easily be tolerated by fish long-term, but not this high of a nitrite level. This is why you do not cycle the system with fish in it. Or at least it's not recommended.

If you do find yourself with high nitrite levels when you have fish in the system, you can do one of two things:

1) Pray to the Nitrite gods to be merciful to your fish. <------------This will not work.

2) Add salt but do a water change first, say 50% and add back fresh water. Sodium chloride contains the chloride ion which displaces nitrite in the fish's body. This will prevent nitrite from oxidizing hemoglobin to methemoglobin which cannot carry oxygen and the fish suffocate. How much? I would start with 1 ppt (part per thousand) but do a water change first to add fresh water. Then, if the problem doesn't resolve quickly, I would add another 1 ppt every day to 3 ppt. I'm not going to go into more detail than that for now, but will re-visit this topic later.

There are products on the market that can be used to neutralize nitrite, but since we are growing fish and plants in an aquaponics system we cannot put anything that is potentially toxic to humans into the system. Focus instead on creating a healthy bacterial population and you won't need to worry about ammonia or nitrite in your system.

Last, but not least, I checked nitrate which had risen from around 37.5mg/L to > 100mg/L. This is a good sign. It means that a population of Nitrobacter is well-established. It does not mean that every expanded shale stone in the grow bed is covered in bacteria, far from it. That of course is our end-goal, but it's not necessary for the purpose of connecting the fish tank to the system.

Is there a concentration where nitrate does become toxic? That's an interesting topic that I'll address at a later date. Suffice to say that I'd like to keep it < 20mg/L, but people have raised fish with levels > 100mg/L. My goal is to try to mimic what happens in nature, and there the nitrate levels are usually well below 20mg/L, and even < 10mg/L.

The grow bed itself is almost perfect. There are still a couple of areas where the water level is very near the surface of the rocks, but I still have some expanded shale in the basement so I will remedy that at some point.

A very important note about the two bacterial species. The Nitrosomonas bacteria grow and replicate faster than Nitrobacter. This explains why there is a bottle-necking of high nitrite levels often when cycling an aquaponics system or aquarium. So it may still take a while for the nitrite levels to drop as it is Nitrobacter that does the conversion from nitrite to nitrate. Everything seems to be running on track, though, so I am not worried.

Another note is that I checked the temperature yesterday in the cycling system. It peaked yesterday at 67 F! This probably explains why the bacterial colonization has gone so well.

And, finally, a quick note about oxygenation. Here is the sump tank where the Channel catfish will go. When filled to the level of the inflow pipe, it's about 225 gallons. This is after the siphon has broken (I still have to explain the automatic bell siphon, I'll get to that).

There is quite a bit of algae growing on the sides of the tank. This tank will be covered by a tarp and hopefully I'll get around to it today. You should have a tarp covering any exposed surface of water to prevent algae from growing. I've just been lazy. I will get a tarp over it. It is amazing how crystal clear the water is. The media, in this case expanded shale, is very effective at filtering even the smallest particles, even ones that you would think would pass right on through. I think it's due to the way water flows through the shale or any media.

Here it is with the water flowing into it. It's easy to see that this will cause the water to circulate well and get highly oxygenated! I may add a small aerator to this Channel catfish tank. That will help keep a lot of dissolved oxygen in the water.

Remember that it is critical for the oxygen levels to be high for both the fish and the bacteria.

I will get to the automatic bell siphon. Now, we continue to wait on the bacteria. Once the nitrite goes to zero and the rest of the ammonia is gone we will be all set.

 

[DainBramage1991]

Very nice presentation, C-4. I look forward to seeing more.

The channel catfish should be nice and happy in the sump tank, there's plenty of room for them in there. Adding an air pump is a good idea, it will help maintain a good O2 level during the times when the bell siphon isn't dumping water into the tank.

As for adding carbon to the filter system, think of it as cheap insurance. While it's not specifically necessary, it is a good preventive measure. It will absorb many of the foreign toxins that tend to show up in the water, for example: soap, which is toxic to fish even in very small quantities. This is probably less of an issue with aquaponics systems than with indoor aquariums due to their much larger water volume.

 

[C-4]

Very nice presentation, C-4. I look forward to seeing more.

The channel catfish should be nice and happy in the sump tank, there's plenty of room for them in there. Adding an air pump is a good idea, it will help maintain a good O2 level during the times when the bell siphon isn't dumping water into the tank.

As for adding carbon to the filter system, think of it as cheap insurance. While it's not specifically necessary, it is a good preventive measure. It will absorb many of the foreign toxins that tend to show up in the water, for example: soap, which is toxic to fish even in very small quantities. This is probably less of an issue with aquaponics systems than with indoor aquariums due to their much larger water volume.

I think the additional aeration is a good idea since I'll have a decent amount of fish in the system and, as you point out, there is the "down" time when in between when the automatic bell siphon is not draining the grow bed and oxygenating the water. The sump tank does have a large surface area so I don't think the aeration is critical, but I have it so I may as well use it.

 

[C-4]

Minor update: 05/28/2014 Ammonia now zero but Nitrite still high.

The ammonia is now zero. This is one of the requirements to connect the fish tank.

[span style='font-weight: bold;']The nitrite is still sky high. The fish tank cannot be connected to the system until this drops to zero. It may still be a while.[/span]

There is no point in checking the nitrate level as it has to be in the tank because there is no way for it to get out so it will continue to be off the chart. There are no plants to absorb it and I haven't done any water changes. Same with ammonia. Now that it is zero it cannot go any lower so there is no point in checking it. So from here on out I will only be checking on the nitrite levels until it drops to zero. Hopefully it doesn't take too long.

More to come.

 

[DainBramage1991]

It's a step in the right direction. From my experience, it should take another week or so for the nitrites to drop.

I suggest checking it every other day, if you can squeeze the time out of your busy schedule.