How much space do trapdoor snails need?

Question

How many gallons per snail? Apple? Ramshorn? MTS?

Answer 1

The recommended amount of space for the apple/mystery and giant ramshorns are 2-2.5 gallons per adult snail: http://www.petfish.net/articles/Invertebrates/mystery.php
http://www.petfish.net/articles/Invertebrates/ramshorn.php Use the actual volume of water, since you should have the water level below the rim for both of these - the mystery snails will need the space to lay their eggs above the water level and the ramshorns will occassionally leave the water too.

I didn't find much about a recommended stocking levels for trapdoors, but since they're approximately the same size as the mystery and ramshorns as adults, I would use the same.

This still allows plenty of space for them to breed, and you should still have good water quality.

The Malaysians are much smaller, and you can probably start with about 5-10 per gallon.

With good a good food supply and good water quality, you'll have more of all of these soon enough.