In my experience Cyano
Bacteria (red slime) is most likely to form from elevated Nitrate levels, and / or water changes that use city tap (phosphates/silicates). Cyano
seems to compete with hair algae for nutrients, or a shared nutrient, and you seem to get a mass of either, but in a constant balance.
I've also noticed a relation between DSBs and Cyano
with the red stuff always forming on the top of the DSB
in a large, smooth patch, or on plastic/vinyl equipment, but rarely any place else such as LR
. Other correlations I've noticed is that red slime in a tank seems to severely stunt the growth of desired plants. Likely competition for certain nutrients once red slime gets established since bacteria will win all contests in this manner.
My suspicion is that there is some type of gas exchange going on with a DSB
at the surface tha feeds red slime, but unique to a DSB
since I rarely see red slime on healthy live rock. Maybe the ammonia/nitrite break-down that occurs right at the surface of a DSB
allows red slime to grab nitrate before it can be grabbed by other competitors and turned into free nitrogen. I've also noticed that older reef tanks, even those I know are being replenished with city water, seem immune from red slime. I suspect a mature tank has enough biological competitors to starve red slime out of existence.
I have a 55 reef that gets minimal water changes, is literally *over-skimmed*, and has non detectable nitrate levels. Regardless, there's always a patch of red slime somewhere, but it never exceeds a total surface area and my corals are doing just dandy. Unless I see some other problems going on I simply ignore it since it's likely consuming something I don't want in the tank in the first place, and I'd rather deal with looking at red slime than Nitrate.