OK set up a new tank live rock and sand had it running for about 2 weeks then too water to get tested all was good. then added cleaner fish snails about 6 in total. 2 Giant crabs not sure of name and about 5 hermit crabs. I have a 27 gal tank and about 2 days after added cleaner stuff the tank started to turn green on the tank walls and rocks. did do something wrong? or what