To get this out of the way, I have a 55 gallon tank with moderate stocking, 1 angelfish (her mate died a long time ago), 1 apisto mcmasteri, 2 honey gouramis, 1 sunset thick lip gourami, 12 x ray tetras, 12 cories, and 1 BN pleco. The nitrogenous wastes are 0 except for nitrate which varies...