So, we had purchased our fish and put them in the tanks and once again, we have met with disaster. We still have our seedlings growing in our rockwool and naturally, we figured that we needed to have the fish in the system for a few days first to get the water nice and yucky so that the plants would thrive. Turns out, this is not the case and I am really happy that I was not able to purchase more expensive edible fish to start with because they would all be dead right now if we had put them in the barrels.
What we learned from this disaster:
Just because you have a 12 inch drop from the garden to the barrels does not mean that you have enough O2 in the system!
You still need a bubbler in the tanks. The more O2, the better! Some people actually put bubblers in their grow bed or PVC pipes. By not having enough O2, your fish will die quickly. Apparently, they also need more O2 at night than they do during the day. We have not yet figured out why this is.
Even if the fish are small, do not start with tons of fish!
The number of fish that can be sustained in your aquaponic garden is probably fewer than you think! It is not just based on the number of gallons in the tank that you are using! This number is more directly related to the amount of grow bed/PVC pipe area you have plants growing. The fewer plants you have, the fewer fish you can sustain because they can only remove so much stuff from the water.
You need to “cycle” your water!
“Cycling” your water may not mean what you think! It is not just simply turning on the pump and letting the water run through your system. For this, you need a better grasp on why aquaponics works. Simply put, “cycling” is the process of getting your water where it needs to be. When cycling with fish, you want to start with very few fish and work more in as you go. This process will take weeks, if not months to get your tank to have nitrate/nitrite/ammonia levels that you want to achieve. Fishless Cycling is much faster and easier and takes only 10 days to three weeks to complete. Then you can add all of your fish at once, avoiding a pecking order when you have carnivorous fish in the tank.
What is “fishless cycling” and how do you do it?
Fishless cycling is the process of obtaining your ammonia from something other than the fish and leaving the fish out of the system until the tank is balanced, creating nitrates, and ready. In order to do a fishless cycle, you will need to obtain some ammonia. Sources of ammonia include: bottles of pure 100% ammonia from hardware or cleaning stores, “humonia,” ammonia crystals and dead tissue. Some are difficult to find or expensive and some are just plain weird.
Liquid ammonia usually comes in a gallon bottle and is about 10 ppm ammonia to water. It costs about $20 per gallon and can be poured directly into your tank. This is not always easy to find. Ammonia crystals can be found online but is sometimes costly. It is dry and can be added directly into your tank as well. “Humonia” is human urine. Human urine is free and readily available, but in order to use it, it is best to put it in a sealable container and let it sit for several weeks while the urine turns into ammonia, so that you know what kind of levels you are using. You could just pour it into your tanks, but then you will have a difficult time measuring how much is in there because it takes a while for it to turn into ammonia. You also have the concern of bacteria of some sort in your own system (body) or the system of your…”donor.” Lastly, you could allow a couple dead fish to decompose in the tank, but again, you are going to have the same control issues with the amount of ammonia you are using as with the humonia, as well as the concerns about releasing something you don’t want in the water. We are actually thinking about testing this way first, since we just had so many dead fish in the tank. We are thinking that there is a good chance that we have a lot of ammonia in the tank already!
Once you have decided on your source of ammonia. Add it to your water, keeping track and noting how much you are using in order to get to ~.5 ppm on an ammonia test kit. Continue to add this amount every day until your nitrites appear, then decrease the amount of ammonia you are adding by half. Continue to do this until your nitrates begin to appear. Once nitrates appear, your nitrite levels have gone back down to zero and your water is ready for your fish. Until your nitrates have begun to appear, in my opinion it is a bad idea to add fish to your system. If you decide to use the fish to cycle your system, it is best to just add a couple of fish and keep increasing a little at a time until you have reached the recommended number of fish based on the following formula (It is going to be fewer fish than you think!) at aquaponics.net.