I live with nats,haha.A lot of experienced growers say you should learn to live with them especially if growing in soil.You get rid of them and they just turn up with the next lot of soil or coco.I just keep on top of them with sticky traps.They say the 3 pronged approach is best.Bottom feeding,sticky traps and predatory mites that stay in the sustrate and eat the lavae.You can't see them.I think they die when they have nothing left to eat.Iv used them once and they were the onky thing that cleared them up,for a few weeks.I can't remeber the name.Google predatory mites for fungas nats.Iv still got the empty bottle I can dig out if you dont find it.I got them off ebay of all places,ha.The lavae eat the roots but they say they do no harm umless you have a serious infestation.Iv never noticed any harm.