Originally Posted by GuOD
I've just seen a bunch of empty shells around my tank. They're astrea snails I believe (LFS
called them Turbo Snails though). ...
I tested my water to make sure and all was good wtih my test strip, but nitrates showed 20ppm....
Are you sure the shells are empty? I mean... have you yanked one out and busted it open? Just a guess here, but I bet the snail is still in there and it rotting away might be the source of your nitrates if 20ppm is out of the ordinary for you.
I've lost maybe 1/2 of my turbans over the last 3 months and I think it's because with those pointy shells, when they pitch off the top of a rock somewhere they auger into the sand bed pretty good and can't right themselves. The tronchus snails, with a rounder shell, don't seem to have that problem. My water parameters are just dandy and nothing else is effected, so I'm just guessing I have clumsy snails.
A month or so ago, I just happen to be looking at one on my rock just as the lights went off. The lights must've startled the snail because at that very moment, it lost grip and took a high dive off the rock into the sand. I watched it for about 5 minutes trying to right itself. No go. I finally had mercy and got the long tweezers out and righted it.
You might dig one of those shells out and see if it's truly empty before you give your crabs twenty lashes for something they might not have done. (Although I wouldn't put it past them.)