I've used a lot of stuff trying to control spidermites, but what I've been using lately seems to be the best, it's a combo of Insecticidal Soap, Pyrethum, and Sulfur. To achieve this combo I use two producs from Ortho- Insecticidal Soap, and 3 in 1 pest and disease control, 1 part each, these are both good sprays for people trying to avoid the hyperchemicals.
However, this is just the base of my spray. I also add a couple of drops of front line for long lasting control, and
floramite cuz it's the shit.
Make sure that you throughly get the entire surface of the plant, top and bottom of the leaves (will be easy to tell as the 3 in 1 and the Insectical soap both leave a nice shiny layer).
After you've sprayed, give your entire room two or three more applications on three day intervals. After that you should be clear, however if you're not, don't be alarmed, just be vigilant with the spray whenever you see them, and stop spraying 2-3 weeks before harvest and you shouldn't have any nasty residue.
Now, as far as your question is concerned. I would get the baddest bug bomb you could buy to start off with, not the little five dollar raid bomb, more like the 30 dollar nuclear holacaust bug bomb.
Let it sit for 24 hours, the fogger will probably say less, but you want these bastards to suffer.
After that, go ever every square inch of the interior of your room, and exterior if it's a box/tent with bleach. Bleach has been proven to kill cancer cells and HIV cells.
If you have any mites in the box after that, then good luck cuz those things are like rambo.