red slime remover is relatively cheap. It's an antibiotic, and can kill cyanobacteria. (believe it or not, not all cyanobacteria is bad.) lol. But, for the most part, if you have a lot of red slime, add more water flow, feed less, reduce lighting, do water changes, siphon it out as much as you can, increase natural filtration with an algae scrubber and if all else doesn't work, then use the red slime remover.