@Bmacpiper
Welcome back to forum, where everything nice happens, and everything nasty is explained, like fungus gnats… Seems this year most people is plauged with them, like me too. I used Hydrogen Peroxide water mix to kill wet top soil fungus…(used to much apparently, cause it killed my youngest plant, like nute burn… Shriveled up like skin in water to long, and croaked.) Got Neem Oil ordered, probably get yellow traps, got coillidle silver, got friend has some DE willing to share. So ima get rid of these gnats for sure. Was only watering seedlings/new veggies, 1 time a week with 1 cup water. Top soil would not dry, yes have fan, maybe humidity is to high for grow bags to fully dry. Which caused top soil fungus/mold, which in turn attracted fungus gnats. 
and now I got spiders too. I see coming next, spider mites… DSOB!! I CAN’T WIN FOR LOOSING. Now I’m a plant killer. In all my years, this is first plant that I have ever killed. 
Yes, I’m old school. I’m not using all these super nute grow products… nor grow tents, ac, and high dollar grow lights, for 1: I can’t afford it. So needless to say, I have small plants. Gonna suck come harvest time. Oh the only nutes I’m using is “miracle gro.” 
well sorry to give you such a long hello and story. But hope everything goes well with you and your grow. Have heavy Harvest.
If you want to come see my grow, Just click on the blue words below,
“1New Patchwork at Night”