i have a 75 gal reef tank .it is 6 months old .icycled it with 100lbs. of live rock and 100lbs of live sand.i use a protein skimmer ,wet dry filter uv sterilizer and 2 powerheads for circulation.fish include 1 powder blue tang and 1 6-line wrasse.i have 1 elephant ear,3 corals and 1 crocea clam.my question is i am covered up in green algae on the glass and brown algae on the sand.once i clean it off it comes back in 8 hrs or less.it seems to get worse when i feed the filter feeders dt's phytoplankton 1/2 tsp.every other day.i use 2 metal halide combined with 4 actinic 12 hrs on 12 off. is this to long ?my tests are ammonia-0 nitrite-0 nitrate-0. i use chemi-pure and poly-filter in the sump and i do weekly water changes. my wife tends to over feed when i'm at work, but idon't think this is the source i my problem.i don't use ro water however i aerate and use a poly-filter in a 20 gallon aquarium set up to treat my water for aweek before putting it in my reef tank. any body have any ideas? thanks