The best chemical I have ever used and still use to this day is 'EndAll'. It comes in a yellow spray bottle and can be purchased at stores such as 'Wallmart' or 'Home Depot'. It is very safe to use on the plants and you can give them a good soaking and not have to worry about burning them.
One thing I would be cautious on with any spray is to make sure it doesn't drip into the soil. I usually put plastic over the base or tip the plant sideways and spray, and then shake well before reverting to it's regular angle to avoid dripping into the soil.
Another thing to remember is to spray the underside of the leaves first and then the tops. Get it all soaked and don't miss any spots. If you do this in two sessions, such as the second time waiting about three days, you should have no problems anymore. Than check the plants closely for the remaider of the grow. If any are seen moving do the two spray process over again. I have never had to repeat the process this stuff is so good.
Hope this helps and good luck on your grow. It is important to take care of mites as quickly as possible, because once webs show it is usually too late.