Red cyano bacteria is usually a nutrient, flow, lighting(old bulbs)problem, or a combination of them that causes it. Have you checked your nitrates and phosphates recently? I've found increasing your alk a bit helps get rid of it also. Red slime remover or chemiclean work very well if you need immediate results. Just make sure you follow the directions and siphon as much out as you can before treatment. If you don't, the dead cyano will cause a nutrient spike in itself. But, if you don't fix the root of the problem, it will return. Also keep in mind, it decreases the O2 saturation in the water. I usually do it at night when the fish are no so active and not consuming so much O2. Turn your skimmer off and remove any carbon during treatment also. I haven't had it return ever since I got my orp up over 400. I run ozone, but it's doesn't come on unless the orp reading goes below 350, and that hasn't happened in months.