During my last flush and feed, I noticed all these little gnats. At first I thought they were in the room that I was performing my plant maintenance, but after looking closer in my grow lab I saw them.
Fungus Gnat
In my research as to how to solve this problem I came across three viable options. 1. Hypoaspis Miles, which is a mite 2. Nematodes, which look like a worm. I found a nursery that carried the nematodes, but at $30 a box which I felt was too much for the small amount that I needed to treat. 3. Sand, which is a cheaper option. I choose this option due to where the gnats were coming from, which was not just the surface, but from the drain holes as well. So I ended up taping up the drain holes along the sides of my pots and filled the pots with sand to the top (about an inch). I also poured sand on the floor of the grow lab and placed the pots in the sand to cover the drain holes along the bottom of the pots. A gnat life is so short that I hope to see a noticeable difference by the end of this week.
San Box of Pots
Jt420grow's Blog 