Hi,
I'm new to auaponics. Here’s where I’m at currently…

System is now 2 ½ months old and the nitrites peaked and then went to 0 about 4 weeks ago.
PH is 7.6, Ammonia is 0, Nitrites 0, and Nitrates 0
16 cf grow bed filled with pea gravel
75 gallon fish tank
Cycle via pond pump and bell siphon every 35 minutes.
100 gallon air pump and stone
Krill Fish feed

Problem: I stared stocking my tank with more and more large feeder goldfish (about 1.5” in length on average).
My goal was to get to about 350 with the assumption that this amount would be roughly 7 lbs. of fish (1 lbs. of fish for every 10 gallons). But before I got to 350 I noticed that my goldfish were starting to die at a rapid rate (10-20 per day). I did a little research and it seemed that they were infected with Ick or Ich. I went to the pet store and bought a plant friendly treatment and a tank heater. I did as instructed (added the treatment to the water, heated the tank to 80 degrees and also added new fresh water for about 3 days). I’ve used all the treatment, but am still seeing a loss of 5-10 fish per day – I’m now down to around 100 fish.
I spoke to Oliver at aquaponicsusa.com. He suggested I post here to get some advice. He did think that I may have loss of fish for a few other reasons besides the infection/parasite. Possibilities could be not enough air to the tank, and not enough feed for the fish (I was feeding them 1 teaspoon of food twice a day – based what I was instructed at the pet store).

Any recommendations would be much appreciated.

Thank you!