A friend told me this which makes a lot of sense:
Alright, if you have a snail explosion it is a clear sign there is a waste control issue in the tank. Snails only take over a tank if there is enough food. There should not be enough food in a tank to allow for this to happen. A snail infestation is a clear sign something is out of balance. I run 3 different tanks, all densely planted low tech and high tech. I have bladder snails, MTS, and ramshorns. Some tanks have one species, some have two, maybe all three. Usually though one species dominates in a particular tank. There is rarely a problem with too many snails. I never remove ANY of them and I don't have any snail eating fish either. MTS are well known for turning the gravel/sand. All these species make quick work of plant debris, that is if they fish and shrimp don't beat them too it.
I have some sort of nutrient issue in my two high tech tanks. I knew it pretty quickly from a sudden drop in grown then different algae out breaks in both tanks. The problem with my plants lead them to reduce their "niche" in the tank. They are not consuming what wastes they were before. A month later there is a increase in snail populations in both tanks. Tanks have been running for years and snails have been present for years. I honestly am never concerned about the snails. Their numbers can go up and down depending on how well the tank is balanced. ATM both are poorly balanced and that is my fault. What exactly the problem is I could not tell you yet. What I see are not problems in there selves, but the effects of something else. Like the saying, "Everything happens for a reason."
