sand bed algae?

[fishman7us]

First, a little history. Irecently moved from a 46g bow front to a 55g because I sold the bowfront and bought and started a 175g Oceanic bowfront. The 55g is the "temp house". when I made the move I went from CC on the bottom to a 1" sand bed. All went great for a few weeks and then I started to notice clumping of the sand, the sand is all clumped up on the surface with green algae of some sort. How do I stop/prevent this? What do you sand bed keepers do to keep your sand clean? I have a few hermits, astreas, nassarius. I have about 50lbs. of LR, skimmer, I run purigen and carbon through a magnum canister, and a small power head for more flow. The tank is mostly FOWLR and some shrimp, crabs, and a feather duster. For fish there is a Sailfin tang, Foxface, Chromis (2), Firefish, Yellow Diamond Goby, Cardinal. Any Ideas? Mithrax? I dont want to be plagued with this in the new tank. Thanks Jason. P.S. I know how big the tang will get and he just a baby and will be moved soon. He was a gift.

[burks]

With out seeing the algae it sounds to be a Cyano Algae out break.