Your tank is new and algae blooms very common. Looks Iike green hair algea. You will almost certainly run into diatoms as well. I totally agree with last post as well. RO RO RO
!!!! Must have for any reef tank Will save you money in long run on buying water from LFS
. Filter guys is a good site.
Your best bet is to clean by hand ad much as possible and get some crabs and snails in there. They may of may not eat it tho. Some tangs may eat but must have big tank for tanks. Possibly lawnmower Blenny.