xenia do not eat phyto. yes let a portion of the the power head discharge blow on it as long as it is not too close.you want strong water movement but not strong water shear. blowing (with a baster or pump) off the areas where the algae is growing. hi po4 and no3 = hair algae the white bead type phos removers leach alumina, most corals do not tolerate it *xenia for one* the iron oxide type is better.water changes barely help for exporting no3 as it leaches out of the rock, sand etc. are you using a skimmer?, kalkwasser? filters? all filters in time become no3 producers, things like bio balls, bio wheels , pads if you are using filters shut them down. try bacteria for the no3. (your tank is beautiful by the way" do you disturb the sand bed? any critters that do? ie: sand sifting stars, fish.good strong water movement is a deterrent to hair algae. you need to look at what you are putting into the tank, foods, additives, brine shrimp are out of sight with po4. the phyto will benefit your rock and sand bed, almost all corals are carnivores. it is a major polluter also.