Having had tanks with snails and no snails, there's pros and cons to both. If all you're looking to do is stir up the sand a bit, I probably wouldn't get snails. Like others mentioned; once you add them it can be hard to get rid of them, and to keep them from spreading to other tanks via nets, plants, filters and ornaments. I currently am using assassin snails in each tank to hopefully eradicate everything but the assassin snails. In a perfect world/tank, I'd have not added snails. My reason for adding them was the snails did a alright job on algae on the glass and they were pretty/interesting to watch. Now that all my tanks are overrun with them, and I have a breeding tank I want to keep snail-free but cannot, I regret getting them.