Get a clean up crew with red-legged and blue legged hermits, and snails. Also, do you have any tangs in your tank? They eat algae. I like the desjardini, purple, and sohol tangs, but the sohol is usually aggressive. Lawnmower blennies love algae too. Also, what are your alkalinity and calcium levels? Low alkalinity and calcium will help problem algae instead of coralline algae. Try a 2-part calcium buffer system like Kent's Tech CB or Two little fishies c-balance. Check phosphate and nitrate levels. They should be as low as possible. If they are high, try a phosphate sponge in your sump. If you have high nitrates, do several water changes a few days apart. Phosphates are a common cause, and if you don't have a phosphate test kit, you need one soon. Test your source water (tap water or RO water), and if that's got it in there, you need a Deinonization filter on the RO unit. Another source of phosphates is fish food. If you feed too heavily, then you need the sponge I mentioned.
Good luck
Sonny
