Aquaponics 101 – Still so much work.

After a week in the pond the Tilapia seem quite happy. I am still feeding very lightly (1 cup twice a day) until my bio-filtration system kicks in. The grow beds really are an unknown to me, and apparently can take up to 8 weeks for the bacteria to start working. I know that my grow beds are inadequate for the volume of fish and water that I am trying to support, so I have been considering adding a stand-alone bio-filter until my grow beds start working.

I have bought a simple aquarium test kit because I was really worried about the Dissolved Oxygen levels. I also got an air compressor for each of the ponds and am now pumping air directly into the ponds. My readings on Saturday after a feed were as follows;

Temperature : 26 degrees

Dissolved Oxygen : 6 mg/L

Ammonia : 0.8 mg/L

Nitrite : 4 mg/L

Nitrate : 10 mg/L

pH : 7.25

These all seem within the parameters for Tilapia, except for the Nitrite which according to my test kit, is in the “toxic” range. I’m sure that it is just confirmation that my bio-filtration is just not properly established yet.

The water is a very dark green colour, which the fish like because they are still rather shy (except at meal times), and to improve this somewhat, I think I’ll be installing UV-filtration this week.

The plant growth seems good for what I have planted so far, with the gem squash and strawberries thriving, but unfortunately the first lot of bean seeds just rotted in the very wet gravel. I was however, able to save one lonely bean plant. I have now planted more (different) beans, coriander, two varieties of tomatoes and parsley. I am waiting patiently for the eggplant and pepper seedlings to do something in the seed beds. I have decided to plant olives on the slope above the back retaining wall, and we have been hard at work planting flowers in beds and building stairs down to the greenhouse.

The greenhouse door is now on and I have had to fix the plastic which blew loose at a join during some high winds. We have had quite a bit of rain in the last few days so I can do a partial water replacement in the ponds from the rainwater tank if the Nitrite levels really start to bother me.

I am being guided to a large extent by the behaviour of the fish and the plant growth, and judging by these indicators, my system isn’t that bad. The fish are eating heartily, but lightly, and at their size should be consuming 3% of their body weight per day (450 fish x 105 g average weight= 47 kg of fish x 3% = 1.4kg of feed per day). I am probably feeding at about half this rate to cut down on Ammonia production.

They are now literally eating out of my hand. The swirl around at feeding time with their big mouths open and I can literally pop the pellets in. Here are some photographs.



Enough for now.



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