snail infestation

Snails are easily controlled by limiting their level of food. If you have an algae problem don't expect to have one for long. Then, once all the algae is gone, the snails will die off to something more manageable.

Also,
Controlling the amount of food you feed your fish will also limit the amount of snails you have. I had some snails (never a problem) before I introduced guppies but I noticed the guppies actually eat snails when they are babies and the shells are very soft. I also saw one determined female eat a cluster of eggs and really, ever since I got those guppies I haven't seen more than one snail at a time for a good long time. I'm also pretty sure it's the same snail (its rather large lol)

I think Clown Loaches eat snails as well as a few other fish but the trick is controlling the food source...

You can kill them all with a copper treatment but that really screws your tank up forevermore.

There are a number of fish that prey on snails, but whether they suit your needs will depend on the available bio-space in your tank and what stock you already have.

There are chemical treatments, but I would never recommend them in the least. Putting toxins in your tank is just a bad idea all around.

While you're working out longer-term solutions (possible snail eaters, correcting feeding/cleaning habits etc), handpicking snails can do a remarkable good job at keeping their numbers down if you simply make it a habit to pull visible snails. I've gotten pretty good at fishing 'em out with my planting tongs. I also keep an eye out for snail eggs and net them out whenever I see 'em.

If you've the stomache for it it and have omniverous fish, squishing them against the glass kills the snail and gives your fish a treat.