most likely diatoms. a pic would help though. if it is diatoms, its usually a waiting game. they feed on silicates so once the silicates are out of your system, it will die off. your problem may be your water though. do you use rodi
? if you dont, you should probably invest in one, or at least buying distilled water from a store. you put this in the reef section, so im guessing you have corals? the green algae is most likely hair algae. this is a harder problem to solve. do you test for nitrates? if so, can you tell us what it is? it could be nitrates or phosphates that are the problem for this. easiest way to get rid of trates is weekly 10-15% water changes. thats almost a necessity in reef aquariums. If your trates are low, its phosphates. less feeding will help with that. whatever it is, good luck. it takes a while to get rid of hair algae. there are chemical means of killing it, but with corals, i would choose a more natural approach, as stated above.