The population size will be dictated by the available food. If there is a large supply of food and algae, the population will increase.
It's fairly easy to reduce your snail population, if you want. Just make a 'snail trap' (take a plastic bottle, cut it in two, approximately one quarter of the way from the top. Remove the cap, stick the top into the bottom, so that the narrow opening is inside, and put a vegetable in the bottle. Then put the snail trap in your tank, turn the lights off and come back a few hours later and remove the trap, and a bunch of snails. Repeat as needed.
In some of my tanks, I just use a spatula to squish a bunch on the glass. It's a great treat for shrimp, fish, crayfish, or even other snails.
I don't recommend ever using a pesticide. If you have a high number of snails, and you kill them all off at once, that will likely kill off many other tank mates, from the spike in nitrates and ammonia.