I know I'm gonna get yelled at for suggesting this, but here goes...
After I followed all the great advice I received in AA forums, multiple large water changes, siphoning off, reduced feedings, upgraded skimmer, increased current, even got rid of two fish and moved a third to another tank and my cyano
In the end I gave up and treated my tank with Poly-Ox. Made by Kent Marine. After about a week I noticed the Cyano
was dieing off. I have an old canister filter that I rigged up to use like a vacuum cleaner. I filled it with carbon and cleaned all the substrate, dumping the cleaned water over a poly pad back into the sump. I did one more water change and have had little to no problem with Cyano
since (about a month). Whenever I do see it creeping back I pull out the canister and sweep it up again.