The fugus gnat stops here.

I have had them twice . The first time was in coco coir (cannabis) . it was bad bad lol I hate those bastards. Mosquito bites  is what I used and never really got a handle on it. They were in my drains in my house etc. I had never had them before. So months later finally they were freaking gone! The second time was recently and it was at work (house plant). I swear I have spider senses when it comes to those little bastards and was able to kill with mosquito bites and yellow sticky pads. Caught it early. This is also another reason I just went to dwc they are not a fan. Looks like you are getting a supply drop . So have at them. 

I hate those fuckers, I have smoked a bunch of them, lol. My first two grows was from clones (Venus Fly Trap) and they came with the plants. I bought the sticky pads and they caught a bunch but it was neverending. When I started watering from the bottom it got much better but it didnt get rid of them.  

Amen! clones, potting mix, and any other new introductions to the garden/ grow room can be possible sources. Went organic, was doing passive hydroponics w coir/perlite mix. Too wet, along with some other problems.  Cleanliness really is next to godliness. Or for you atheists it's KEY.  Some call them FILTH flies.  It go's back to the clecha that. An oz of prevention is worth a metric ton of cure. And the insecticide is systemic, so I avoid treating after the budding light cycle commences.  I have had good success so far. Also, do not leave tents open more then needed.

They can sneak into a DWC bucket and really thrive! a drop of Dawn dish soap can help between bucket changes but thats when youre changing out water. best thing in DWC is to cover the Hydroton and eliminate a moist environment. i use a paper plate or two