@Lazerus00 Those guys can be pesky huh? Back when I was first doing this and still figuring things out (9-10 yrs ago); I got into a period where I had those darn gnats all the time. This was well before allowing myself to read online or what not; so I had no clue what they were. One of the few things I had tried was Neem and as well I had done a bug spray formula from Jerry Baker (tea, soap, nicotine, Listerine etc). Also I guess I had done the predatory lady bugs, who loved dying on the hps's haha.
Finally I broke down and had to find out somehow what these little bugs were. So I contacted a local University and got to a dept. that would test / identify bugs. I took a specimen in and got to talk to the head professor there.
So, I asked "What are they?"
He chuckled and replied "They are fungus gnats"......"It means the soil is too wet"......"Just because a soil looks dry on top doesn't mean that it's dry"...."If you let your soil dry out between waterings, they will go away on their own"
I thanked him and left; albeit not feeling overjoyed at the answer I got heh. I started letting my soils get drier before adding water, sometimes right at the edge of drooping (happens right). At any rate, in about 3-4 weeks, they were gone!!!
Never saw any fungus gnats after. This was also when I set one of my golden rules for myself; "that a plant will not be wet longer than 24hrs". I alter my watering quantity and medium water holding to attain this. One exception is at up-potting; I will allow 3 day period there I guess.
-I have seen gnats one time since then and that was when I switched to doing things right and setup a 1hr drip system. Since soil was moist all the time, the gnats came back. I stopped the drip after testing specific elements and the gnats went away.
Unfortunately, I cannot suggest the best "treatment" as none seemed to work for me. Save for letting soil be drier.