what? Vinegar to kill gnats? Dude, use mosquito dunks. They are a couple dollars at homedepot. Justtear off a quarter of a dunk and let it sit in your water overnight. When you water, the gnats larvae wont be able to live in the soil. After about 36 hours, no gnats. Just give it the dunks like once every 4-5 weeks. Like after a flush? or ever every other flush?