fungus gnats! tried nearly everything in the course of a year.....

Maybe give this a go. https://www.rollitup.org/general-marijuana-growing/310069-praying-mantis-pest-control.html

I had a gnat prob I put screen in the bottom of my pots then a inch of perolite on top the gnats were going in the bottom of the pots covered the top with sand and mixed in beneficial nemetodes to all my soil. I didnt see a gnat after a week of doing this.. I tried everything else and it just slowed them down before the beneficial nemetodes.

ive got this problem im using something called GNAT off but its not much use the sticky fly catchers are good but i have placed 20 plastic cups around my grow room and ive poured a cheap version of red bull into the cups withn two days all the cups are full of dead gnats ive now got sand on top of my soil and this is a constant battle but the red bull i found by chance i left a glass out overnight and spotted it had about 5 dead gnats in so i tryed it and hey presto they must be atracted to the sugaR

i am so sick of them gnats i been fighting with them for weeks now.. and worst i just starting seeing thripps.. there is an all out battle going on right now.. i just started my main offensive tonight, i hope its effective..