Snails. Are they pest?

Those look like ramshorn snails to me. And I agree with the "Snails are our friends club". Especially Malaysian Trumpet Snails and for the most part ramshorns.
 
I got some in on some plants I bought and at first they were awful. They multiplied like crazy...until I got more frugal with my fish feeding. Now I have a few here and there and they eat the algea. If you don't overfeed you shouldn't be overrun with them. Mine are not brown pond snails though. The ones I have are light to medium grey and round, max size about 1/8 inch. The first one I found I thought was a baby mystery snail (footprint is even very similar) but it never got any bigger so I knew it couldn't be. Anyone know what kind of snails they might be?
Does anyone know if leaving the shells from the dead snails in the tank will add calcuim (for my plants)?
 
I overfeed on purpose. Sometimes my 3 HUGE (golfball sized) black mystery snails get algae on their shells, and all the ramshorns, MTS, and common snails (every little guy in the tank!) migrate over and eat all the algae, then go back to their buisness. I also have 17 brigs, and I figure if I'm going to have 2 species of big snails, why not have a bunch of smaller ones too? I have them in all of my tanks, and I love 'em. They do a great job on algae and uneaten food, and it's way more natural to have 4 or 5 different species of snails all helping to clean. They also act as canaries to bad water, I've heard, and they'll fall to the bottom and go into their shells if their is a toxin (ammonia, trItes, trAtes) in the water. I give snails a :thumbsup:
 
AquariaCentral.com