What is the best supplements and how often do people add these really. I have a 29 Gallon Tank with a Clarkii Clown, Percula Clown, Pigmy Angelfish and a small purple Tang with 8 crabs, 5 snails, Emarld Crab and a Cleaner Shrimp. Oh ya, a Mantis Shrimp which I can not catch. I try to do water...