After about 3 months of having my first tank i noticed a small snail crawling around at night... 1 month later there were 5... now there are around 11. I'm starting to think theres a snail infestation going on there. My tank is a 20 galon, so its not too bad right now but my question is, are they good? Do they help out? Or should i get rid of them? And if so, then how? Is there a fast way or just pick them out one by one