I've had a pretty significant cyano issue going on in my tank for several months. Nasty stuff - it was growing in sheets over my gravel and LR. I tried everything to get rid of it - changed the bulbs, frequent water changes, phosphate reactor, etc., etc. I could blast it away or even suck it out with a turkey baster and it would always come back. The strange thing is that my water params were all right on the mark, including zero phosphate with a Merck test kit - everyone always says to check PO4 first if you are getting cyano. I get decent growth on most of my coral, too. The only bad things about cyano seem to be it looks bad and it can smother smaller-sized frags.
When I was out in Portland last month, the guys at Upscales recommended I try this product called Chemi-Clean. I'm very leery of "reef safe" chemicals like that (whatever it is - they don't tell you), but the guys at Upscales use it, and their tanks are spectacular, so I decided to trust their advice. I put it in last week, and within the 48 hour treatment period, nearly all my cyano withered away. The instructions say a second treatment might be necessary. A few days after the first treatment, my gravel started getting slightly brown, and there was something coming back on my LR. I don't know if it was the cyano coming back or some other algae, but I decided to do the second round of treatment just in case. The second round ended just two days ago.
I'll just have to see how things look in a week or two. The good news is that none of my LPS, SPS, or the few softies I have seemed to notice the Chemi-Clean at all. They're all still very happy - perhaps even more PE than before. I read on RC that cyano may exude a mild toxin, so maybe nuking it made the corals happier.
If the cyano doesn't come back for a few months, then I'll be fine with just re-dosing with Chemi-Clean if I need to. If it's sooner than that, I've read some people on RC have had good success with Erithromycin (sp?). But I'm hoping I won't have try that.
Randy - feel free to check in with me in a couple weeks if you're still having cyano issues. I should know by then whether the Chemi-Clean provided a long-lasting solution. Of course, every tank is different. If there's some kind of ongoing condition that's givnig you the cyano, it will come back after any treatment.
Jeff (vol_reefer)