Okay, I did a stupid move and got some duckweed from a local forest and tried to put it into my tank. I placed them in my half gallon tank for two weeks to see if they had any animals on them and, for the most part, they didn't. So I transfered them to my tank and a day later I noticed these tiny black bugs on the roots of the duckweed, on the top, and near the water line in my tank.
I don't have a camera that can photograph them well but they are very tiny, almost aphid size. They are round and have 6 tiny legs and they don't really move around a lot. I looked around to see what they are but can't get an answer.
In addition to this, how can I get rid of them? My tank only has two snails in it right now, 4 plants, no fish.