the plate only lasted a couple weeks after being added. we woke up one morning and he wasn't do too well. i tried to get him out, but it was too late. everything but the fish, crabs, and shrimp died within a couple days. all the softies, the snails, and a feather duster. we've never had the house sprayed on the inside, and nothing at that time had changed. the snails in my fresh water tanks (we have a 39 in the living room, and a 14 cube in my sons room) are all doing great. all water comes from the same source.