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DIY Aquaponics FAQs

18 Aug DIY Aquaponics FAQs

How do I build an aquaponics system?

To build the ISB 2′ x 4′ design, please refer to this ISB 2×4 Design Guide. For a 4′ x 4′ design, please visit this site.

How much will building a system cost?

For total costs of the materials needed for the two ISB designs, please refer to the 2′ x 4′ ISB Design Materials or 4′ x 4′ TX Design Materials lists.

I am a teacher and don’t have enough funding to build a system. How can I obtain funding for my aquaponics system materials?

Right now, the Institute for Systems Biology is working on a crowdfunding campaign to help teachers like you obtain funding for building a classroom aquaponics system. We also recommend Donors Choose, a crowdfunding website specifically for education projects. Just create an account, follow the instructions and create a project to be funded. In this case, that would be your aquaponics system. If you are using Donors Choose, nearly all of the materials listed can be purchased from Donors Choose approved vendors. Click on the following for the Donors Choose 2×4 Materials List or the Donors Choose 4×4 Materials List.

What type of fish should I use?

Typically, aquaponics enthusiasts use Tilapia because they’re incredibly hardy, grow quickly, and can be harvested as a food source! Tilapia require slightly higher temperatures, so a small tank heater may be a nice addition to increase their metabolism and help them grow faster. If you’re not interested in harvesting your fish, goldfish and koi are great alternatives. People have also experimented with crayfish and freshwater shrimp.

Do I need to change the water in my system?

Because the water is being cycled through the system, there is no need to change the water. Some water may be lost through evaporation. However, if you decide the water level is running low and needs replenishing, proceed with caution. Adding water to the system can throw off the chemical balance of the system, so add small amounts of water frequently to compensate for evaporative loss. Also, because there is chlorine in tap water (used to kill bacteria), you should ideally let the chlorine “gas off” before adding it to your system. This is as simple as filling up a bucket with tap water and letting it sit, without a lid, for 24-48 hours.

Is there anything I should be adding to my system?

One great part about aquaponics is there is very little maintenance required once your system becomes stable. In a stable aquaponics system, the only daily addition required is fish food.

Is it okay to have algae buildup in my system?

Generally speaking, you want to have as little algal buildup as possible. Algae thrive in areas with a lot of light (from the sun or a bulb), but they also use much of the oxygen that would typically be available for your fish. To reduce the likelihood of growing algae, ensure all tubing and tanks in your system are black or opaque so they block as much light reaching the water as possible. This sometimes also means covering your fish tank as much as possible, while still leaving room for oxygen to enter.

How long can the fish survive if the electricity were to go out?

Ideally, you should have a backup power source or battery for situations like this. However, in the event that you do not, a less crowded fish tank means the fish can survive longer without extra oxygen. Be sure someone is checking the system daily.

Why did my fish die?

If you have just started your system and put fish in, it may be the shock of a new environment that caused them to die. If your fish are used to warm climates but your water is too cold, that could also be a factor. If you have not added bacteria to the system yet, ammonia isn’t being converted into nitrate for your plants to take up; therefore, the ammonia buildup may have killed your fish. Overcrowding the fish tank can also stress out fish and cause them to die.

Why is the dissolved oxygen (DO) so low in my tank? Is that bad?

Ideally, you’d like to have about ppm oxygen in your tank for healthy fish and plants. If your dissolved oxygen is less than that, it may be due to the high temperature of your water (as temperature and dissolved oxygen have an inverse relationship) or an algal bloom. One way to increase your dissolved oxygen is by adding aeration pumps.

What should I do if my pH is too acidic? Too basic?

The water in your aquaponics system should be between 6.8 – 7.0; however, others have experienced success slightly higher/lower as well. If the pH is too acidic, add calcium/potassium carbonate (in the form of sea shells). Add in small doses. It is much better to make small but often changes rather than a large change at once. If the pH is too basic, add a very small amount of 18% phosphoric acid. The pH will not change immediately, so wait multiple days before adding more and checking the pH. Also, high (basic) pH can lock up necessary nutrients that your plants need to survive. This can cause slow plant growth or cause plant death.

My plants’ leaves are looking yellow. Is there anything I can do to fix that?

In this case, it is recommended you add pure iron chelate to your water for the plants. It makes iron soluble in water and thus, more accessible for the plant. In addition, it is also used as a way to treat a plant that is producing insufficient chlorophyll.

How do I establish healthy bacterial colonies in my system to ensure healthy nitrogen cycling?

Your fish need bacteria to break down their ammonia and make it less toxic, but your bacteria need your fish to feed them the ammonia so they survive! We recommend adding the appropriate amount of nitrifying bacteria for your quantity of water, and also adding small tilapia fingerlings (or just a few large tilapia). This will ensure your bacteria are being fed and are growing, but there won’t be more ammonia to convert than they can initially handle. As the tilapia grow and produce more ammonia, the bacterial colonies will be large and established enough to handle it!