I'm currently thinking that perhaps I will break down the tank and treat the plants with several doses of peroxide and a round of erythromycin. I think I'll get rid of my current gravel, dry the tank out, scrub it with peroxide, wash it thorougly and leave it dry for a week or so. When I set it back up, I'll just buy a new filter and start from scratch. I can use water from another tank to help cycle it, but I'm in no rush. Since I agree that the lighting is probably at least contributing to the problem, I think maybe I'll try some little floating surface plants to block the light, and if that's not enough I'll play around with the lighting more. I'll definitely leave it set up with plants only for awhile. Hopefully all this will be enough to kill any traces of the cyanobacteria!!!