I found the same stuff, I finally got rid of it by increasing my water flow, normally I had 2 marineland 440 (I think that the filter number, may be 400's) hob
filters, and a pump in the sump that returns the water @ a rate of 1200 GPH
. I added 2 900GPH filters cross blowing 1 across the front of the tank and 1 across the rear so that the tank kinda looked like a whirlpool. Ran it like that for about a month solid during the day, drove the fish nuts but in the end I no long have the cyano
. I do have small patches of it but the yellow tang seems to liek eating it so I haven't killed it off completely.