Just wanted to post my experience with chemiclean for the record. I had a huge cyano problem - worst I've ever seen in any pictures on this message board. It was over everything - all the LR and substrate, even starting to grow up the glass. My LFS suggested chemiclean and I used it as recommended on the bottle. A little over 24 hours later - NOT A TRACE OF CYANO IN MY ENTIRE AQUARIUM. I kid you not. Great stuff! Works as advertised! Didn't harm anything in the tank and I had an assortment of fish, inverts, and corals when I did this. So, if you run out of options or just get too frustrated, give chemiclean a try!