probly thrip mate talk to your guy at the hydroponic shop he will show you in the rite direction . had them to start off and apprently they are sapposed to be hard to get rid of but i had this stuff i cant remember wat it was called but it got rid of everyone of them.
Another thought... fungus gnat larva will look like little maggots. White with black heads. Mites and thrips ought to be up on the plant, not under a pot. I'd lean toward soil lice, though it could be something else. Can you give a pic, or at least a description?
To my knowledge springtails ain't that bad and will not infect the plant with diseases, munch up it's roots, or damage them in other ways that I know of... Search, here and in google.