Gnatrol or mosquito bits will kill the larvae in your soil. Both have bti in them and that is what kills the larvae. The flying ones are adults and they try to burrow into your soil to lay more eggs and the cycle repeats. Wack your pots and you'll see some gnats flying but they are slow. Kill them by hand or vacuum them up with a shop vac. Main thing is killing the larvae in the soil. They eat the roots, then turn into flying gnats and the cycle keeps going. You can also try a layer of diatomaceous earth on the top of your soil and bottom feeding helps too.