I believe I made the mistake of thinking my system had cycled and so I added 6 bluegill fish to now 150 gal system.  I have 16cubic feet of grow media , 1/2 is expanded clay pellets and the other is volcanic stone.  Water pH is 6.9, temp is 74 degrees and I added some nitrifying bacteria I purchased from the Aquaponic source store.  I have had to make a 50% water  change every week to keep the am…