K, well I am NO expert, but i did a quick search so i am literaly copy and pasting off other websites. Heres a couple i could find ----
-"This may work, First if you have any clams remove them from your tank and pick off and kill the snails you see the brush the shell clean to remove any eggs. I would take a small plastic container like a 1 Qt. take out food container with lid. cut around 6 small holes at the side bottom edge big enough for the snails to crawl in. I would then bait it with chopped clams w/ garlic to attract them in. Sink it in the bottom of tank and change food to something else if the clams don't work.
Ive also read that Scooter Blennys will eat them
Good luck"
-"Fresh water dip all your rock for about 30 minutes. All the nasties will vacate the rock but quick."
-"When I first got my clam I had a outbreak of Pyramid snails. I added a 6-line wrasse and they all but vanished. I thought they were gone for good. But when the 6-line jumped ship the snails re-appeared. I added a new 6-line and the snails again appear to has vanished again."
Sorry! Hope this helps, good luck