I switched to coco a few months ago and since then I have had bad fungus gnat issues. I am using mosquito dunks in the res and Microbe Lift Mosquito Control in the res's as well. I have yellow sticky traps for the adults.. Also for the past 3-4 weeks I have been misting pyrethrin on the coco surface when I see adult flyers.. so I basically have not seen any adults in at least 3 weeks now. I see one every other day or so and that is when I nail the coco surface with pyrethrin and it kills them off again. I am still getting tons of larvae in my 4 x 4 trays though, you can see them wiggle and hop around on the water surface. What can I use to safely kill the larvae once and for all? the dunks or the licrobe lift stuff is not working apparently (had had them in all my res's for a couple months now). I bottom feed in 4 x 4 trays.