Cut a 20 oz soda bottle in half so the top half will invert into the bottom half. Put cucumber in the bottom of the bottom half and put the top half in the bottom half. Secure together with fishing line. I make the line long enough that it will hang over the top edge of the tank while the bottom sits on the bottom of the tank so I don't have to put my hands in the water all the time, just lift it by the fishing line. Put it in the tank and wait. The snails will go in the bottle and not be able to come back out.
Also remove any you see by hand. Look for jelly looking things on your glass and squish those...those are eggs. And mostly do not over feed your fish