For what it's worth, I was getting bothered by the amount of cyanobacteria invading my 6 month old tank and affecting my corals, so I resorted to dosing Chemiclean. It worked as advertised, pretty much wiping it out. I did the recommended 20% water change after 48 hours and was able to siphon up the last remnants of it. No ill effects to the fish or corals. Pretty happy with a better looking tank. I'll work on the cause, which I think was that my nitrates had nearly bottomed out.