what plants do you have? I have lowlight plants and dose nothing and they are growing like crazy and propagating. perhaps you could go a little more low-tech if you want to keep snails.
if you can get just a cheap critter-keeper type thing from walmart or a petstore, the apple snails will be just fine in that with a water change once a week or so. as long as they aren't freezing the temperature is no problem, and they will actually live longer at room temp than they will in a tropical, heated tank. their lifespan depends upon their metabolism and growth rate, which is sped up by warmer temps and slowed by cooler ones. a room-temp snail will live 3 years, a tropical-tank one will live 18 months or so.