cheap way of killing pest! will it work?

I was wondering since plants can grow in water as long as you have air pumps giving it air like in hydroponics. what if you grow in soil and tribe of bugs are havin orgies and reproducing by the masses? could they all die if you had those pot in a big container with air pumps and lots of water. than by hanging your plants with the pot fully underneath the water with the leaves being above water for a few days. can that kill all the gnat flies and spider mites? and will the plant die?

...do you have spider mites?...try neem oil, and don't forget to spray the underside of the leaves (most important)

...adult gnats are harmless, it's the larva in your soil that you have to worrie about. The larva eats on your roots. If you let your soil dry all the way out (until your plants wilt alittle) before you water again, this will kill 80 % of the larva. I use Ivory or any biodegradable dishliquid to fight the gnats. Just a few drops per gallon of water. Get some fly tape and hang them all around your room to catch the adult gnats.