My local pet store told me that trumpet snail won't eat plants, but that they will clean algae and such. Sounded pretty good to me so I added about 10 or so several days ago. It seems like they hide away during the day--the burrow into the substrate, and it seems like they burrow right next to plants into the roots more often than not. What are they doing? Is mixing up the substrate benificial at all or is it harmless? Stiring the substrate would seem as if it should have some ramifications...