The system has now been running for a while, the fish are growing very well and so have the plants (some more than others).
I purchased the kit you see in the picture a few months back, thinking that I should test the water immediately to make sure that we were going down the right path. I just let it slip and since the fish seemed very happy and the plants were growing, I assumed that everything was on track.
Yesterday, I finally took some courage and tested the water since I was planning on taking the chard out of the system to eat it (that’s the whole point, right?). I ran every single test that comes into the kit, i.e. pH, ammonia and nitrites levels and carbonate and general hardness.
pH = 7.4
Ammonia = 0 mg/L
Nitrite = 0.1 mg/L
Water is soft and carbonate hardness is 20 mg/L
The results show that the fish are not generating enough ammonia to cause toxic levels of any sort. In 500L of water, those tiny Silver Perch (only 10 of them) is not enough density to cause problems. That’s my conclusion so far.
Of course, this has also its downside, i.e. not enough ammonia == not enough food for the nitrifying bacteria and, as a consequence, not enough food for the plants. Which explains something that both Danielle and I had been considering for a while. The plants are growing however we are not experiencing those “dramatic” growths as described by the multitude of aquaponics practitioners around the world. We thought that the lack of sun would also be a problem however, since we moved the growbeds into a much sunnier spot, I believe that lack of sun light is no longer a problem and, if that was the case, we probably would have higher levels of ammonia or nitrites in the water (i.e. the plants wouldn’t be growing well, not due to the lack of nutrients but due to the lack of light).
So far, I am very happy with how this prototype aquaponic system is going!