Red,green,brown slime is cynobacteria. This organism is everywhere on the planet and many believe it made life possible. It uses CO2 and light to produce the sugar it needs to live and then it uniquely takes athmospheric nitrogen and creates compounds useable by living things,including;amonia,nitrite and nitrate in sort of a reverse denitrification(cycle of life).
To control it you need to control CO2. Some advocate light control. I don't since I believe it's less stressful for the other photosynthetic organisms in your system to reduce the CO2. Also if you turn out the lights for several days and reduce the cyno,it will come roaring back when you turn the light on unless the CO2 issue is brought into balance. Balance meaning that there is enough CO2 for desireable organisms(corals ,coraline) to use without excess for the cynobacteria.
Cynobacteri outbreaks in aquariums seem to occur more frequently in the fall but I don't think that has much to do with the sun but rather the fact that many homes get less air exchange at this time of year than they had been getting during preceeding months. Since the athmospere in your aquarium equilibriates with the air,if the air around it is higher in CO2 than usual the CO2 in the tank will be higher than usual and it might take a period of time for organisms to use it up leaving the leftovers to the opportunistic cynobacteria.
There are a number of things that can be done to control CO2 before resorting to lights out or an oxidizing chemical such as Chemi Clean.
Remove waste via agressive bubbly skimming this will also blow off CO2. Remove any dead animals or rotting material( CO2 is ultimately produced in the breakdown). Improve air exchange with good flow particularly at the surface. Clean any filter media to remove decaying material. Suck out the cyno mats with a turkey baster. Puff off your rock to put decaying detrius into the water column for export by your skimmer.Likewise ,gently puff the very top of your sand ,if any. If the air in your home is high in CO2, consider running fresh outside air into your skimmer intake. Consider dripping limewater at night it uses CO2 to produce bicarbonate needed by corals.
Good Luck
