I am battling the same problem. The clown loaches don't seem to eat all kinds like mentioned but i have a yo-yo loach and he is going to town on these things. I don't plan on keeping him forever as I have Discus but for now he is doing the job and will keep him to make sure they are all gone.
I do not recommend any products you add to kill snails. I did this many years ago and it wiped out everything in my tank. They are very harsh chemicals so don't use them.
Lettuce core sunk in the tank will attract many of them and simply remove it and throw it away the next morning. You would be amazed how many you can get this way.
If you can remove most manually then get a yo-yo loach you should have it all done but don't get rid of the loach right away if you don't want it as there will be hidden eggs that have not hatched that will and then it starts all over again.
Also I even tried the Asassin Snail, they eat other snails and it did not work so skip them as they are not cheap either.
Good Luck
