My tank cleared up. I'm not sure what the correct levels should be. I'm sure different fish require different levels. Have Tetra's, Peppered and Green Cory's, and a Rubber Nosed Pleco. Gh - 120, Kh - 100, Ph - 6.8, Nitrite - 0, Nitrate - 0. Where's the best place to check on what is best for...