Mike,
I believe I am agreeing with Randy in saying that although Chemiclean may solve your issue short term, you will still not be solving the root of the issue which is an excess of nutrients. I found that it is best when you rid cyano without the assistance of addatives. That way you know that you beat it for sure because it starved and then died away as opposed to being killed off by chemicals. I am speaking from experience.
You must remember that cyanobacteria is in your tank always. You will never get rid of it. It is just a matter of getting the proper nutrient balance to keep it invisible so to speak.
Is it possible your sand or rocks might be leaching something that is fueling this outbreak?