Spider mites are probally the most prevalent pest to inside growers. There are many ways to erradicate these critters but can be broken down into two types of methods. These methods are chemical or organic.
With any pest erradication program where you are depending on a chemical, be it organic or synthetic, it is best to cycle between three different pesticides for optimal results and to ensure the critters don't build an immunity to them.
I've found that spraying with a pyrethium based spray to be very effective. Buying one that is combined with garlic would work as a repellent to these pests as well. The only problem with this is recently there have been shown to be pyrethium resistant mites. The treatment regime with this should be at least one spray a week, but no more than two. Don't think that more poison concentration will help remove them faster as it may only lead to your dissapointment as you see your plants suffer from burning. When spraying make sure that the underside of the leaves get just a much of a generous spraying as the tops.
If things have got right out of hand and nothing else seems to work you can count on flea bombs purchased from local supermarket. Be warned as they are full of dangerous poisons and the use of these should be greatly avoided within the last few weeks before harvest. The regime for these are one a week until problem solved, this is usually one week but occassionally you will need the second one. Make sure to turn off all exhaust fans for two hours from the time that the bomb is initially going off. After this two hour period is over turn back on exhaust fans and air out room thoroughly. Do this when the lights are out as a room full of fumes has a habit of exploding when a heat source or spark is present. These are so effective because the actually break into every part of the breeding cycle killing mites in all stages.
The recent success in mite eradication has come from the availability of a pesticide called Avid. Many growers swear that this is the only thing that really works without reinfestation. It is extremely important to kill them off completely and not start breeding resistant populations.
The most popular of the organic pesticides in recent times is neem oil or neem based products. These do work well in most cases. The treatment regime for these is no more than every three days and should be avoided in the last couple of weeks due to the fact that it can give the flowers a dirty flavour when consumed.
One completely chemical free way to eliminate mites is by manipulating the humidity in your grow room to above 80-90% for no more than three days. Any longer than this and you're asking for mold. This works because the mites absorb the extra moisture in the air and literally explode due to absorbtion of too much water.
Another manual way to go about things is to go in every day and give the plants a liberal spraying with plain water on both tops and bottoms of leaf sufaces. This physically knocks them of and disturbs there patterns as mites may not move for three days at a time. With this, as with the previous method, beware of mold.
With any treatment using chemicals be carefull to follow instructions and follow good safety procedure. It's not the best feeling to be stuck in bed for a day due to inhalation of chemical vapours.