Thanks for all the suggestions.
Chye Huat: Been contemplating on sea cucumber but I've got a powerhead very near the sand bed...worried it might get sucked in....hehe. might just do that!
Tineng: Yah, I've bought those blue legged hermit before but they seem to like to crawl over my acros all the time. Didn't like the idea and got rid of them in the end.
So far, I've got 1 emarald crab, 2 sally light foots, about a dozen dwarf hermits, nerite snails and nassaurius snails too but doesn't seem to efficient
How about kole tangs etc???