Hi! I have a 12 gallon square fresh water fish tank with some cherry shrimp, one nitrile snail, octo fish, and a few guppies. I started buying guppies when my tank was about 6 months old and fully cycled and the parameters were stable and still are at Ph 7.4-7.8, No2 0, No3 0, Nh3 0 Nh4 0-0.25...