2 turbo snails cleared my startup 10g of all green hair algae in about a day and a half. Get some and give them a week--if they haven't cured, or at least greatly improved, the situation in that time take 'em back and trade up to the next item on the list.
these guys cleaned it so fast that I was afraid they were then going to starve. But here they remain, cruising the glass and everything else. Only downside is that they are like litle bulldozers going over the rock. If you want a frag or other object to stay in place you had better weld it firmly down. epoxy, despite working fine on aptasia-smothering, does not appear to work attaching frags to rock. possibly not enough crevases for it to fit in? i dunno. But that's a problem for another day.