If it's a new tank, then its normal and will go away, but if it really is red slime, it looks really thick, is a dark red almost maroon color, and you can peel it like carpet, then you need to get rid of it. It's not actually an algae but Cyanobacteria. It shows up from excess nutrients from overfeeding and the best way to get rid of it is to siphon ALL of it out. Just turning off the lights won't due cuz it can live a long time without light and just the ambient light from the room is enough to keep it alive. Putting more flow was mentioned but that works best for prevention, not when you already have it. You can also use chemiclean which you can find from your lfs. You just have to turn off the skimmer and remove any carbon. It works extremely well but you have to make sure you use the exact amount for the amount of water in your tank. A 55g doesn't hold 55g of water when its filled with rock and sand. If you put too much in, it will poison your tank and kill everything in it.
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