Yeah, this type of snail is nearly impossible to get rid of unless you tear down the whole tank and disinfect it. I had a huge outbreak of them in my son's community fish tank. There were probably 300 of them in the tank. They dont hurt anything, they are just really ugly to look at. Especially that many. I completely tore down the tank and started anew. No problem since then. If you dont want to tear down the tank stick a small plastic cup with a very small opening just big enough for the snails to get in and put lettuce in there and by time morning comes all the snails will have congregated on that cup and all you do is take the cup and snails out and dispose of them.
