usually, water rich in dissolved organic compounds and phosphates is prone to cyano outbreaks. as long as there are phosphates and nitrates, some small, nonzero number of cyanobacteria can survive, waiting for the opportunity to multiply rapidly.
small doses of the antibiotic erythromycin will take out any red slime (cyanobacteria) in your tank. dosage is roughly 200 mg/100 gallons. hope this helps...
On the antibiotic erythromycin idea...
I don't think that I would use a antibiotic in the tank. You would also kill the wanted bacteria with the unwanted ones.
The best way to deal with this stuff is just keep the tank in check... water changes, keeping the quality of the water in top shape, and most of all: making sure that you have proper water movement.