Yep, they multiply fast!
As long as your water readings are fine, you wont have too much
.
If you think you have loads by day, just take a torch to the tank by night!
The population of snails can only be as big as there is enough food to support for, so if you have lots of snails, that means theres lots for them to eat. Removing snails would just mean that organic matter goes uneaten, so bacteria would take their place in consuming it. Really no difference except you cant see the bacteria, and it may happen slower, I'm not sure.
So basically, apart from complete extremes where you have like a 4 inch thick layer of the snails in a small awkward shaped aquarium there could be oxygen problems, don't worry about it.
Any snails you remove will be replaced as others grow anyway. I think I remember reading somewhere that the snails breed slower when the population is more dense. The only reason to move snails would be if you don't like the look of them.
I like the snails. do a good job moving fish/shrimp waste under the sand so it doesn't look unsightly and the plant roots/bacteria in the substrate can get at the nutrients
.