poolkeeper1,
Now you are getting into a real
hot topic. The use of carbon sources to control cyano.
IMHO, using carbon sources is in the realm of trying to out compete cyano for nutrients using bacteria.
If you stop and think about it, bacteria are about the only organism that may have the potential to out compete the cyano. They both can derive their C,N,P from food, N2 & CO2.
Unfortunately, CO2 is normally available in more abundant levels in our reef tanks than the levels found in the ocean.
N is available in our reef tanks in abundant supply.
You can try to lower your phosphate level to zero if you like, but there will still be more phosphate available in our reef tank then in the normal reefs found in the ocean.
This leaves the possibility of using strains of bacteria that would be able to out-compete the cyano. I have not read any articles where these strains of bacteria exist. I would be interested in any information about this possibility.
Unless there are strains of bacteria that can out-compete cyano, I don't see carbon dosing as a viable option to control cyano except to reduce the phosphate and nitrate to very low levels. IMHO, the cyano will end up laughing in our face.