If you don't have any crabs, the cucumber is the way to go if you want pure white sand. I already have hermit crabs and a couple of emeralds, so I recently got 2 fighting conchs in my 180g. I'll probably have to get more, but they are amazing. I was unaware of their abilities until I tank-sat one for my friend while he got his system up and running (he got it as a package deal.) My sand literally looked better overnight, and it is obvious which side of the tank he preferred.