Snails......Son of a....

I have a problem..... I had a 20Gal tank about a year ago and purchased
a couple snails. Well, they had little snails! And hundreds of them!
Now, I have a 55 Gal tank that WAS sans-snail. I actually boiled my
decorations before putting them in the new tank!

So...I go to petsmart a couple weeks later to get plants. We noticed in
the plant tank that they had snails. I asked a couple people there
about the chronic snail problem and they said that these dont
reproduce....

Well, long story short, there are about 1000 snails in my tank!!
Had-a-snail seems to mess with my levels too much to use. It killed
some fish last time. Im not sure if it was ammonia from the dieing
snails (dont remember) or what, but 2 days after had-a-snail....I
had-3-dead-fish.

Any thoughts on how to kill these things? Also, Im moving in 2
weeks...wanting to transport some water.....but no snails....

Thanks!