I have had great success with azamax in getting rid of fungus gnats. I mix it in with the water when watering or fertilizing. Mosquito dunks work well in resevoir but I grow soil. U can also get some stuff called gnatrol as a soil drench that contains the same bacteria as the mosquito dunks. The bacteria is Bt israelienesis. There are different types of Bt controls for different little nasties and Bti kills gnats. When I use azamax as a soil drench I also use tanglefoot. It is a VERY sticky goo that traps the adults. Fungus gnats are attracted to the color yellow so I buy a bunch of yellow paper plates at The Dollar Store, spread the plates with Tanglefoot, spread the plates around the grow area and catch the adult gnats. I also buy latex gloves to wear when spreading the Tanglefoot. The stuff is a drag to get off of hands or anything else it gets on 'cause it is so sticky.