If you have a problem with algae, you can get a dry, plain sea sponge for about two dollars at WalMart in the soap and bathing section and scrub it off very gently. Be sure to keep his flesh moist by dipping him back in the water for about 20 seconds when doing it, though. It comes off pretty easy for me, and my snail tries coming out and crawling on my hand while I'm cleaning him, LOL. Oh, and don't use soap obviously.