Snail outbreaks are a feeding problem.

Pest snails (bladder, pond, ramshorn) hitchhike in on plants and breed to match the food available. A population boom means you're overfeeding โ uneaten food is fueling them.
Feed less and remove uneaten food. Drop a blanched vegetable or a snail trap in overnight and scoop out the snails that gather. Squashing a few daily steadily lowers numbers.
Assassin snails hunt and eat pest snails without taking over (they breed slowly). Some loaches eat snails too. Avoid chemical snail killers โ they can crash your tank and harm shrimp.