December | 2017 | Two Miles From Nowhere

two green half-IBC totes with plants, a blue plastic barrel, and a green shade cloth wrapped around anothe IBC Tote. — My Backyard Aquaponics System

I created an aquaponic system in my backyard partly out of necessity, and partly to test the concept for use at the family farm.

When we decided to move, I had to figure out what to do with the plants and fish from our backyard pond.

A pond with a blue iris and a turtle basking in the sun. — The original pond, with a turtle named Dog.

Frankly, I didn’t want to invest the time and effort to recreate the pond as it had been, and I had been reading a lot about aquaponics systems, so I decided to just do it.

How the Aquaponic System Works

The basic concept is to use a medium such as gravel or formed clay pellets to grow plants in, instead of soil. To accomplish this, a nutrient-rich flow of water is applied in a way that allows the plants to get the nutrients they need while also providing oxygen to the roots so the plants are not drowning.

Gravity forces water in fish tank to feed into radial-swirl filter, which then feeds into the grow bed, and then draining into the sump tank, where a pump returns water to the fish tank, repeating the cycle. — The Linear Flow of the Aquaponic System

My system is based on a gravity-fed cycle where the water starts at the fish tank and flows to a radial filter to remove solids, then to a grow bed, and finally to a sump tank, where the water is then pumped back up to the fish tank.

school of goldfish in a large plastic container with some black plastic tubing and an underwater light. — The goldfish that power my backyard aquaponic system, as seen through four feet of water filtered by the system.

It is not setup in the same linear fashion as the graphic depicts, instead, it wraps around a 90 degree corner. However, the water still flows as depicted above.

Top down view of aquaponic system components, showing arrangement around a 90 degree corner, where the radial-swirl filter is the corner point, with fish tank extending horizontally to the left, and the grow bed, stacked on top of the sump tank, is extended vertically. A diagonal pipe returns water from the sump tank to the fish tank. — The view of my aquaponics system from the top, showing the actual layout around a 90 degree corner.

The grow bed features a bell siphon which causes the water to slowly rise in the grow bed until the water level reaches a certain height that activates the bell siphon.

Growbed filled with white gravel and green plants with a black plastic insert in the lower corner, which keeps the gravel contained and away from the bell siphon. — Bell siphon made of white PVC pipe inside a black protective column.

The bell siphon produces a rapid release of the water from the growbed into the sump tank.

Because the water drains very quickly out of the growbed, it causes oxygen to be drawn down into the plant roots within the grow medium, which allows the plants to breathe and thrive, instead of drowning and dying.

The grow bed also contains a lot of surface area in the form of the gravel that is used. Each piece of gravel provides area for algae and bacteria to grow on, and it is these little organisms that do the work of converting fish waste into nutrients that are easily used by the plants.

Half an IBC Tote, painted green and containing a variety of pond plants. A board crosses the top of the tank, bearing the growbed whic overlaps a corner of the square tank. — The sump tank with pond plants and mosquito fish.

The water that goes into my sump tank also feeds a bunch of pond plants I had, and then the water is finally sent back to the goldfish, filtered and clear.

I also have a colony of mosquito fish that live throughout the system and eat mosquito larvae. These mosquito fish are amazingly effective, and we haven’t had any problem with mosquitoes. Your local county government might even provide them free of charge- it’s worth checking into.

sump tank half full of pond plants, with 45 degree angle pipe coming off of the bottom of the bell siphon from the grow bed above. — The usually unseen back side of the sump tank, shaded by the growbed above.

Materials Used

I bought some used IBC Totes that had contained food-grade glycerin. It is important to make sure your buy either clean IBC Totes or else ensure they were only used to contain/ship food-grade materials.

There are lots of nasty toxic substances that are also shipped in IBC Totes- be sure you know and trust your source so you don’t poison your system (and yourself).

IBC Totes are about 4 feet wide, high, and deep, and come in 275 gallon sizes as well as 330 gallon sizes. You can usually find used food-grade IBC Totes on Craigslist for between $75-$125 dollars.

Plastic cube in a steel cage with a green shade cloth attached via yellow rope and orange clips. — The fish tank is a 275 gallon IBC Tote, wrapped in shade cloth to stop excessive algae growth.

I also used this as an excuse to buy a Sawzall reciprocating saw- which makes the chore of cutting the IBC Totes a much easier task. I highly recommend getting one if you can.

For the radial/swirl filter, I followed the instructions from a video I found on YouTube that seemed like a good design (link below). I used a couple of 5 gallon buckets and a 55 gallon plastic drum that had once been used to hold/transport garlic.

Blue barrel with orange insert, and several white pipes extending out the side. — The radial-swirl filter forces water to travel up and down around a baffle in the barrel, causing solids to settle at the bottom of the barrel and clean water exits at the top.

To connect everything I used a range of different diameter PVC pipe and fittings, and an energy efficient magnetic impeller pump.

I had to special order some things on the Internet as even in San Jose the local Home Depot doesn’t carry a lot of 2″ pipe fittings to connect to an IBC Tote, but there are plenty of options online that should have what you need, whatever type of IBC Tote you are able to find.

Finally, if you use any silicone sealant, be sure to use the aquarium safe type, and be warned- it takes a full 24 hours to dry and cure before you can put it beneath the water line.

Critical Considerations

When you first put together your aquaponic system you need to be very careful about the water quality, and the nitrate/nitrite cycle.

Because I already had an established pond and was able to capture and move a large amount of the water, I didn’t have to wait for the nitrate/nitrite cycle to get in balance.

There is a lot of information on the Internet about conditioning your water and aquaponic system, and lots of people recommend waiting 14 weeks before adding fish and plants. However, there are lots of other people explain how to get things started much quicker by using water conditioning products to remove chlorine and heavy metals, and amonia to kick-start the nitrite/nitrate cycle. When combined with notoriously hardy goldfish, you might be able to establish the nitrite/nitrate cycle in a few days instead of weeks.

Essentially, before plants can thrive, your aquaponic system has to develop the fundamental layer of an ecosystem comprised of the different algae and bacteria needed to process fish waste and turn it into usable nutrients your plants will love. This happens over time as a layer of slimy algae grows on the surface of your fish tank, and in the gravel/medium used in your growbeds.

If you rush the process and introduce fish and plants before the system is ready, you can kill your fish and plants- and then no peppers for you!

bright red habanero peppers in a shiny stainless steel bowl. — First harvest of habaneros.

However, if you do it right you can find that your aquaponic system will outproduce your soil-based garden. If you choose to go with a fish that you can also harvest, you can enjoy your own fresh organic fish, or maybe even sell it for profit.