Aquaponics

The summer of 2009 I became very interested in aquaponics. Aquaponics is the combining of aquaculture(growing fish or other water based animal) and hydroponics(growing plants in a medium other than soil and providing nutrients through a liquid solution). Aquaponics is a significant improvement on these two separate systems. Both aquaculture and hydroponics have a major drawback in that they create large amounts of nutrient wastes. Fish waste has to be cleaned out of tanks and taken somewhere else in an aquaculture system. Hydroponics depends on a very specific balance of nutrients and results in removal of liquid solutions that are high in water soluble fertilizers.

Aquaponics takes the waste of these systems and turns them into inputs. The basic principle of Aquaponics is fish are grown in some body of water normally a tank and their waste products feed plants. Both the fish and the vegetables can be harvested resulting in a much higher calorie production compared to each individual growing systems alone. The fish breathe and poop producing ammonia which if is not taken care of is highly toxic to the fish. Naturally occurring bacteria appear over time that can convert the ammonia to nitrites which is still toxic fish but not as bad as ammonia. Once there is enough nitrites another bacteria starts converting the nitrites to nitrates which is the form of nitrogen that plants like to use and is significantly less toxic to fish. This conversion is key why aquaponics works so well, it takes a toxic waste for one thing and produces food for another. Depending on what you are feeding the fish other nutrients will be available, while other will have to be added.

Check out our flickr page to see photos from the building process and a harvest of tasty vegetables.

For our experiment that went from the fall of 09 to the fall of 2010 we used what is called a flood and drain grow bed system. The system moves water from the tank into grow beds which are filled with some growing medium other than soil,in our case we used hydrotron expanded clay balls. They reminded me of the cocopuffs I loved to eat as a kid and I had to resist the urge to pop a few in my mouth. We used a pump to pump water out of our tanks and up into our two grow beds we made from rubbermaid totes. The water would fill the beds until it reached a certain level. It would then drain out automatically with a siphon back to the fish tank. The grow beds act as a filter for the solid part of the waste. The grow beds also act as the breeding ground for your friends the bacteria. They cling to all the available surfaces, which means you want to look for a growing medium that has a lot of surface area. The expanded clay balls are expensive for large operations but they work great for small scale setups. Most folks that have larger grow beds use a stone mix that works well but is much heavier.

The system needs to cycle before its ready for fish. This allows the bacteria to grow and become stable. If you do not cycle the system before adding fish you are taking a chance at a collapse of your system and a loss of fish. People have done it but the folks that have been doing it for awhile recommend to do a fishless cycle to be safer.

We had no place to put our growing set up besides our room so it meant that it had to be compact and we had to provide our own light. I made a mock up of our room in sketchup and built a few designs and figured out where we could put it and what its exact dimensions where. This is my first of many many plugs for sketchup. It is pretty easy to learn to do basic stuff in it and for me visually seeing things helps me grasp the end product much easier. We found a 55 gallon fish tank of craigslist for cheap, the wood we had laying around but we plained it so it would look nicer, we had recently moved so we had the rubbermaid totes handy. We had to buy piping, fittings, the pump, and a 400w hps light. The light and the pump were the most expensive parts of the set up and also have the cost of running them over time attached to them. The last thing I added that I had around the house was a emergency blanket backstop and curtain to keep the light in with the plants and not blinding us. After we found the tank we found two giant goldfish on craigslist for free so we added them once our system was ready for them. I made a mistake when I first the built the system in that I used copper fittings which can become a problem with water toxicity so make sure to stay clear.

We cycled the system with fish and it was really stressful for all of us so I do not recommend it at all and tested the water with a kit that tested for all sorts of things on a daily basis. While we waited for the system to cycle we started seeding the grow beds with lettuce, basil, radishes, peas, beans and I brought in a few strawberry plants inside to test it out. To supplement the missing nutrients I also added some liquid kelp plant food which made the room nice and stinky for a couple hours after each application.

Everything we seeded grew with the exception of the beans which seemed to stay to wet and they were also old seed left over from who knows when. It was amazing how fast things germinated in the grow beds much faster it seemed than in soil. By December we were eating lettuce and radishes and enjoying our new fishies. We decided to get more fish went ended up being trouble. We did not quarantine them long enough and they brought some disease with them. We had to medivac all of them to temporary tanks in our bathroom where we could administer antibiotics. We lost one of our big fellas and a few little ones and it really tore at our hearts. Who knew we could grow so attached to a fish. The next time we introduced fish we did it more carefully keeping them in a separate tank for longer and making sure they were not troubled. After that mishap our fish friends were much happier and our veggies grew like wildfire.

We made more pesto that winter then we had in the summer. Basil really likes to be grown hydroponically and it really did well in our setup. Ate snap peas in the middle of winter and had hints of peppers by January. Our light and pump were set to a timer that controlled how long they were on. Our alarm clock was the hum of the lights and the sound of water pouring into the grow beds. We tried different light timings but it ended up being around 10 hours a day or so. Thats quite a bit of electricity we were pumping which is one of the reasons we do not have it running this winter. Once it warmed up enough out side we moved it out onto the porch and had the pump run for 15 minutes of every hour which seemed to work well.

We were really happy with our results from our aquaponics setup. If we did it again we would make a few changes but the basic stuff would stay the same. Our new house has a large southern window that I plan on setting up a system that only uses it for its light. We will be using mostly house plants this time around with a few veggies mixed in. If we were in a place were the soil was questionable because of toxic residue I would definitely have an aquaponic setup for summer time growing.

If you want to learn more about aquaponics you should visit http://www.backyardaquaponics.com/forum/index.php they have the most active group of systems and are really helpful with new growers.

Will Allen of Growing Power has a really interesting aquaponics setup set up in an urban area and is providing fresh food in a place where little to no grocery stores or markets can be found.

See you folks next time
Josh

January 18th, 2011|Tags: , |

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One Comment

  1. cyn January 19, 2011 at 2:00 pm - Reply

    you make everything sound so doable

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