I have a bit of a battle in this area going on now...
Lots of options... water changes, sulfur reactors, vodka reactors, dosing, marine pure blocks, chaeto algae, and skimming, and water flow, detritus removal/suspension via flow and sump cleaning, sock/filter-pad maintenance, and stuff like nitrate removal media and bacterial solutions. Lots of these ways take months to work.
Assume you have a decent skimmer up and working?
I would suggest that you do nothing for phosphate removal like GFO for some time as some of these methods require a Po4:nitrate balance to work properly.