Hey fd, don't you just hate it when clones flower like midgets. Why does this happen? Did you take clones from a flowering plant?
I got that problem with gnats a couple of grows ago. That's part of the reason I'm growing hydro now. Once the gnats get into the soil, you're fucked. They lay hundreds of eggs, and the babies feed off your roots till they are big enough to fly about. You see a few, then suddenly they seem to disappear, next thing you know you have an infestation.
The best thing to do is buy a couple more fans and aim them directly at the bottom of the stems. Gnats are very light and they don't like windy conditions, also buy loads of dangly yellow sticky pads so when the wind hits them they go flying straight into them. lol.