[Aqua-holic]

That is a sure sign of copper when you test the water is it testing 0 even a trace of copper will kill inverts. sometimes if copper has been used in a tank previously the residue will remain in the sand, silicone, even glass or acrylic, so it may be residual copper that is the culprit with the drip method how long do you take to acclimate? when you put the snails in are they turned face down? snails that are face up sometimes can't get turned over and drown. Do you have any metal fittings on your tank or on your Ro unit? metal fittings are usually copper or brass and both will cause problems if you don't have an ro unit double check with the place you buy your water from if you use city water it is most likely in that all of our local water has copper in it and some areas have quite a high level