The problem is
these suckers keep getting into my canister filter and breeding like crazy
in there - I can't find a way to eliminate this problem.

Have you tried putting a foam prefilter on the intake? I got a cylindrical
foam prefilter from Pet Solutions that fits perfectly over my Eheim intake, and
it's great at keeping junk out of my filter, including snails. With an
adaptor, it also fits over the intake to my Aquaclear (on another tank),
keeping snails out there, too.

It was only a few dollars -- probably the best dollars I ever spent. I rinse
the prefilter every other week or so, and only have to clean the Eheim media
every six months or so.


Leigh

http://www.fortunecity.com/lavender/halloween/881/