mrg02d - I think your tank is still fairly young, right? Like less than 3 months since you cycled? When you first start up the tank, with the cycling and die off from live rock, learning how much to feed, blah blah blah... nutrients are usually pretty high in the water. In that situation, it's pretty easy for cyano
and other nuisance algae to set up shop. Unfortunately, it takes a while to get rid of it - even if you're doing all the right things. If you're doing the right things, just be patient - you'll beat it.
Flake - agree with thincat... glad you considered it a last resort and you know the cause. So many times, it seems like people just use the stuff in place of good housekeeping and don't try to find out the "why" behind it all.