[fishytime]

ok so the dead rock shouldnt be a contributing factor....perhaps Im a little "Marko rock shy".....Ive just been trouble shooting problems for two years with customers who's only common factor seemed to be the use of a large percentage of dead rock.....


unfortunately then the problem lies elsewhere...... there are a number of contributing factors that cause cyano bacteria (not an algae, so GFO or phosphate reducing products wont help).......cyano is a product of excess nutrients plain and simple (sometimes fueled by lighting).......here's a punch list of things you can try....

increase flow to keep the nutrients suspended so they get skimmed out
reduce feeding (frequency and an amount)
reduce photo period
Turkey baste off your your rocks frequently
siphon crap out of your display
strain all frozen foods
change your bulbs if they are old (I know this doesnt apply to the OP)
increase your w/c regiment perhaps both frequency and and volume
think about your bio-load



these small changes can add up to a big difference......use a chemical as a last resort....I think chemicals are a band-aid solution to an underlying issue