Chemiclean was a miracle for me the first time I used it. It started working within 10 hours, and really had almost everything gone within 48. I'd give it a little more time. It didn't harm any of my creatures.
However, the 2nd time I used it, I don't think it did anything at all, and a couple snails died. So it seems to be hit or miss -- but when it hits, wow, it works.
Just shut down the skimmer and filters while its in there, but make sure to add some oxygen to the tank through your powerheads if you can.
