gnats usually come from soil . but if you got em you gotta kill em before trying to prevent them. i used a no pest strip. you can buy them from a drugstore or target. it worked for me.
Hydro does not atract bugs. Opened doors, material that has been introduced to the grow room. Sounds like you got some kind of source that they inter if your indoors..
i got gnats in my hydro too, i bombed the f ing room
Hydro probably does attract fungus gnats since they are attracted to water and hydro growers typically have more water around.
Bomb with pyrethium (sp)? spray to kill adults. run GoGnat or BT thru your hydro to kill larvae. Clean up all dead plant material and moist spots around the house. Pray.
Gnats and mites are common issues for all growers. Soil tends to have eggs in it but both hydro and soil will attract bugs from the smell of the plants. Its sweet like a nector and other veg eating bugs will find them. You can use fly strips yellow sticky traps, neem,doktor doom bug bombs and things like sm-90 which actually add a repellent to the plant that is no harmful to humanes.