sounds like fungus gnats to me. im fighting them too and its hard to get rid of them all. there are some predatory mites that eat the larvae, and one bacteria i saw that killed them when i was doing research. i decided to just go with yellow sticky traps and sand to keep them off the top of the soil. also i let my soil dry out completely before watering, to the point of the plants starting to wilt just a bit sometimes. im finishing up all my current plants and starting over to be sure and get rid of them all