They get good sized and move pretty fast, so 10 might be overkill depending on the size of the tank. I have 4 adults in my 55, though they aren't my only snails.
They didn't seem to do that great of a job with algae for me, though they did forage up any leftover food. They're attractive enough that even if they didn't eat a thing I'd keep them around.
My nerite snails go for algae very well, but don't seem to go on plants, just hard surfaces like glass and rockwork. They're also attractive enough that I forgive them their failings (lol). Ramshorns completed the set for that regard, they pick plants clean, and will also breed controllably - nerite snails usually can't breed in freshwater, and apple snails lay their eggs above water, so depending on where your water line is, they may not breed successfully in the tank. In months, mine have only produced one tiny offspring.
Depending on what else is in the tank, ramshorn snails plus a shrimp that can breed easily like cherry shrimp would make an impeccable cleaning squad, and once you have populations established, you'll be able to propogate them for other tanks.
