Grey mat algae?????

Brittle Sea Stars are better in terms of fish and invertebrate safeness, more so than Serpent's, but are more a scavenger than a sifter or aerater.
Sea Cucumbers, and Conch snails are ideal, hermits are pretty good as well as sifting gobies, though if you have bottom dwelling animals like clams, anemone's and plate corals, etc. you run the risk of these gobies depositing substrate on them which isn't a good thing (ask Matt R.-hehehe)!

 

i had a tiger tail cuke that did wonders and since its a less colorful ( if it per chance died its not gonna kill your tank) also the snails do ok..i had 8 in a 75..seemed like the cuke did more, JMO..

 

Thanks guys. I've added a diamond goby and am ordering a seahare this week. I'll probably add some nassarius snails as well. I believe now it is cyano, I'm starting to see the red cyano on a couple of rocks.

 

Funny you mentioned sea hare. I just borrowed one from my buddie lfs for my 5.5gal.. I had alot of green hair algae. It cleaned my tank in about 2 day.... Big eater... Had to do a water change cuz it crapped so much.... I had 6 nassaruis snails in my nano cube 12

 

Would vacumming the cyano off the surface of the sand during a water change be a bad idea?