I have a 55 gal fish tank and have had it for over a year I use to have a few dozen fish in there, lobsters, snails, frogs and a algae eater lately after a tragic moving episode my numbers have significantly dropped but now I am having a problem I never encountered before my water is all green and no matter what I do it keeps turning green and now one of my fish have a red bump on the side next to its fin and I don't know what to do please help me