For that size tank you might want to start off with 3-5 Trochus snails and maybe one Scarlet hermit crab. Use something like a Mag-Float to keep the glass clean and either stir up or vacuum your sand bed on a regular basis. If everything goes right all that nuisance algae will be replaced by Coralline algae anyways. There's really no need to rely on an army of invertebrates to keep a tank clean as long as your willing to do a little work. GL.