I have been doing quite a bit of testing with aquaponics over the last year. One of my aquaponics systems is growing herbs and lettuce right in my kitchen. The distance to the stovetop is about 80 cm, how’s that for reducing food miles!
This system is a small aquarium with some NFT channels on top. I made the channels from rectangular plastic air duct, the ones that you can buy at any home improvement shop, they are normally used for kitchen and bathroom ventilation. Water gets pulled through the black filter box on the right and pumped into the channels where the plant roots can take up the nutrient rich water. One channel has 7 planting sites for herbs and the other one has 3, which are spaced further apart to grow lettuce. Since the plants don’t receive any direct sunlight, I had to provide them with some artificial light. Things are growing quite nicely and I often use fresh herbs from this indoor garden.
The fish are growing pretty fast as well, but they will take some while until they are big enough to eat.
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My goldfish have been polluting the water for a little while now and all the plants I have transplanted into the aquaponics grow bed are doing good. A few days ago I decided to add the NFT channel, that I made a while ago, to the system and pop some basil seeds in. The seed packet says that germination takes 15 to 20 days, the seeds I put in started sprouting after 3 days! The picture was taken this morning, 4 days after sowing.
]]>These past 2 months have been very eventful, but we are about settled now. The first 4000 liter fish tank has been set up inside the greenhouse. For now it houses goldfish. We’ll have to see how temperatures develop in the greenhouse throughout the winter. I will probably build a shed around the fish tank and connected grow bed and equip it with a grow light to be able to grow some veggies this winter.
Sorry, no pictures at the moment, as the USB cable for the camera is still in one of the unpacked moving boxes…
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I filled a 250 liter rainwater barrel with aquarium water and put some fish food in there every few days until I had a nice algae bloom.
I went to the aquarium store quite a few times, but each time they where out of life daphnia, I used too see them there every time, but now that I needed them they didn’t have any… typical…
Eventually I managed to buy a small bag. I put them in the green water and after only two weeks the water was crystal clear and swarming with daphnia. Every day I can scoop some out to feed my fish but the supply seems endless.
During winter the barrel froze over and I thought that the water fleas had probably all died, but to my surprise they continued breeding when spring arrived.
If you want to have live fish food during the winter as well, you can set up a culture vessel inside, but you will probably have to feed them.
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After a bit more tweaking, the barrelponics system is up and running! I have put seven little goldfish in that I had rescued from our 800 liter goldfish tank before the big ones could eat them. The little ones overwintered in our tropical aquarium but where now getting big enough to eat the guppy fry, so they needed a new home anyway.
I have taken one of the tomato plants that I had planted in the garden a few weeks ago and moved it into the aquaponics barrel. Another one that is almost exactly the same size will stay in the soil. This should be a nice test to compare how the two plants develop and how much fruit they produce, let the waiting game begin!
I thought I’ll use the long weekend to set up a little half barrel aquaponics system. I still had one of those blue barrels laying around, so I went ahead and cut it in half to create two grow beds. After filling the grow beds with washed gravel and filling them with water the troubles started: I was using a loop siphon to do the ebb and flow in the barrel, but the loop just didn’t work like it should. When filling the barrel, the siphon should kick in at a set level and empty the barrel again, giving the plant roots access to oxygen rich air. After the barrel has been emptied the siphon should break and the barrel should slowly fill up with water again.
My siphon either wouldn’t kick in correctly, leaving the barrel flooded, or it wouldn’t break, leaving the barrel empty at all times. Some more tweaking is necessary for my barrelponics to work. Since I don’t have to go to work today, I’ll have all day to try to get this working.
The nice thing about aquaponics is that it is very scalable and can be set up almost anywhere. If you want to try out aquaponics you can set up a small system to grow herbs in your home. All you need is a small fish tank and a container that can be used as a grow bed. The fish in the tank will fertilize the water with their excrements and the growing plants use these nutrients to grow while cleaning the water.
In a small setup you can locate the grow bed above the fish tank. The grow bed can be filled with lightweight expanded clay aggregate or gravel. A water pump on a timer will fill the grow bed with water and small holes in the bottom of the grow bed let the water flow back into the aquarium. The holes have to be sized to let less water pass through them than the pump delivers to the grow bed. This way the grow bed will fill up while the pump is running. Once the pump shuts off, the grow bed will empty out into the aquarium.
A system like this is called flood and drain and makes the plants grow nicely. In the flood stage the plant can take up water and nutrients and in the drain stage the plants roots have access to oxygen. You can place your setup by a window or, if you don’t have a suitable spot that receives enough light, you can add some lights.
(sketchup model by: Dave)
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My aquariums have a healthy balance of fish and plants. The water is crystal clear and the plants are thriving. I don’t have to do any water changes to keep all levels in the optimum range, the only thing I have to do is top up the water every other week to compensate for evaporation. A well balanced system like this is easy to create and maintain in an aquarium. It takes some experimenting, but once you get the hang of it the maintenance is next to nothing and you can just sit back and enjoy watching the fish.
Intensive fish farming is a different ball game. If you want to make a profit you have to put a lot more fish in your water. The water gets polluted by the excrements produced by the fish, making the water toxic for them. Bacteria that live in a biological filter can convert the highly toxic ammonia into nitrite and nitrite into nitrate. High concentrations of nitrate are still bad for your fish, but they are an excellent nutrition for plants!
You could use the nitrate rich water to fertilize the soil in your vegetable garden and replenish the fish tank with clean water. This would however require a lot of fresh water and a big part of the nitrates would sink deep into the soil, beyond the reach of your plants roots.
The solution here would be hydroponics. In a hydroponics system you grow plants in water instead of soil. The water in a hydroponics setup is enriched with nutrients that the plant roots normally extract from the earth. Small crops like salad and herbs can be grown on a raft that floats on the water and has holes in it for the roots to reach the nutrient rich water. Bigger crops like tomato plants need some coarse gravel or rock wool for support. This grow medium is located in a tub that is flooded with the nutrient enriched water. After the growing plants have extracted the nutrients from the water it has to be enriched again.
Hook the fish farm up to the hydroponics and you have an aquaponics system. The fish provide fertilizer for the plants and the plants clean the water for the fish. The balance in an aquaponics system is much like in my aquariums but both the fish and plant density are much higher. As long as you make sure that this balance is maintained, you can make the aquaponics system as big or as small as you want, ranging from one small fish and one plant to a pond with thousands of fish and an acre sized greenhouse.
A big commercial system isn’t for everyone, but you can have a small aquaponics system in your garden or kitchen made out of items you probably already have laying in your garage or shed. Put a little work into it and you can enjoy home grown fresh herbs and vegetables, without the pesticides!
Looking for information on the subject, I stumbled upon the Backyard Aquaponics Forum, which turned out to be a very friendly community of people with a great deal of knowledge and experience in this field.
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