I have have used Chemiclean in a fish only system, worked great. In my 20 gallon I had a serious brown algae, bubbles, then it turned to cyano.This was after being set up for 8 month, no skimmer. I did water changes, suction etc. to no avail. I finally broke down at the advise of LFS and used maracyn(erythromycin). The Cyano was gone in 3 days. I then began using local purified water only for top offs and water changes and installed a red sea skimmer. My tank never looked better, and has been flourishing ever since!
