My tank has only been running now for less than 2 weeks. I've already gone thru a brown diatom stage and now the last couple of days I've had an explosion of green hair algae. I have 2 cortez hermit crabs and 3 useless turbo snails that I bought last weekend. I use RO/DI water and have no nitrates. I don't have a phosphate test kit yet but have been using Pura Phoslock since start up. I only run the MH's for 4 hours a day. I hope it's just a phase that will come to pass. I have a Cheato clump in my refugium that's growing already. I also use Seachem Reef Salt. I just don't understand all the hair algae at this point.