@Chromophore, Thanks, I appreciate any input. The soil I'm using drains fairly well. These things really became a problem when the temperatures and humidity dropped. I'm running a space heater in my veg room and the the soil dries fast. The plants will droop and sag in 36 hours after being watered if they don't get watered again. So they were getting watered about every 24 hours which, I guess, created an optimum environment for the gnats. I'm not sure how to get around that now other than by keeping the pots full of nematodes.