Home garden Aquaponics
We’ve been experimenting. After reading blogs, watching youtube and reading books we have built an aquaponics system. Its our prototype and it seems to be working well so far.
The basic idea of aquaponics is that the fish feed the plants, the plants clean the water for the fish and everything grows well with much less water and no additives at all.
The nitrogen cycle
Fish produce ammonia and the ammonia is converted into Nitrite and then Nitrate as it leaves the fish tank and lands into the grow bed (garden bed fed by the fish tank). Fish cannot survive in their own ammonia and typically when people are cultivating fish it means there needs to be either a large body of water or the water needs to be changed regularly. In Aquaponics systems the ammonia becomes nitrate and feeds the plants.
The medium that the plants grow in filters the water on its way back to the fish. In many systems there is also a sump tank where that water from the grow bed goes before returning to the fish tank. We have yabbies in our sump tank and this further cleans the water before it returns to the fish.
Setting it up
This is the grow bed made from recycled cladding and old Oregon pergola posts. The first attempt at a bell syphon made from PVC is shown front left. This syphon didn’t work at all. It took ages, weeks literally, to get the syphon thing right. It was an exciting time when that finally worked.
We ran the system for a few weeks before introducing the fish. To get the cycle going we used a small amount of compost and worked on conditioning the water. The water used in this system is rain water stored straight off the roof. The challenges with an IBC tank are getting a balance between heat, light, insulation, algae build up and oxygenation. The water Ph needs to be monitored although the fish species we have are fairly Ph hardy.
The structure here is to create a protection from harsh mid summer to the garden and the fish.
Elements of an aquaponics system
- grow bed is 300 mm (30 cm) deep and 1.2m wide by 2.1 m long (can be longer – up to 2.8m)
- tank is 1000 ltr IBC tank (food grade)
- pump is auto turn off
- sump thank is an old bath tub
- bell syphon is made from PVC piping
- other fittings are all PVC, hose and plumbing joiners
- lining of grow bed is polyurethane pond liner
- medium is scoria
- fish in our experiment are silver perch (strong PH and temperature tolerance)
- top up water is from rain water tank collection.
Aquaponics might seem like a fancy way to have a productive garden but it is more than that. It grows very vigorous plants very quickly and with a sweeter, cleaner taste. Production is ‘off scale’ for a veggie garden. It also uses no pesticides, no nutrient additives or any other additive except water. And because it is recycling its own water it uses 90% less water than a garden in the ground. The 10% is from evaporation and this is topped up by a few litres of rain water.
The whole system has been going for 5 months or so now. This is the way to go even with slow growing fish eventually there will be produce from them too.
We are planning to ramp up the experiment and put in 3 more systems here in Melbourne as a test for the 5eyesfarm in Java where the plan is to set up commercial systems. Stay tuned, discuss here and let us know your thoughts…