Hey Kaspm - you might try other non-chemical means of solving the cyano issue before adding chemicals to the tank, which honestly is undesirable and ideally would only be a last resort. Sounds like you have tried other things, but I'd avoid these chemical fixes like the plague if I were you. They might provide a quick(er) fix, but may not solve the root cause of excess nutrients, inadequate water flow, etc. Think about what you are doing and how it is effecting your tank - you are putting a chemical into the tank that strips oxygen out of the water - this is not a good thing(!), regardless of any temporary side benefit. If you have a skimmer on the tank, that is probably enough aeration, but I'd avoid chemicals if you can. If you are at your wits end, that is understandable too - just know that nothing good happens quickly in a reef tank, not matter what the bottle instructions say ; )