Yes, I have used them and they worked great along with manual removal with a dental tool. We got rid of them all...Anyway we did notice or we think that after the bumble snails had no vermatid snails to munch on they took out a few of our smaller good snails. I put 6 bumblebee in the 300 and they did alot of damage to the vermatid in about 2 months...as of today 8 months later no vermatid and we took out the bumblebee snails...Sal