It really depends on a couple of things.........
PureCrop1 is normally my go to but I have a new recipe that's probably better AND MORE EFFECTIVE. Use only up to 1st week in flowering:
Ingredients:
1. Dr. Woods Peppermint Castile Soap
2. Dr. Woods Tea Tree Castile Soap
3. 70% Alcohol (no higher)
4.
Hydrogen Peroxide (1%)
5. Plain water
Mix 2 quarts warm water (not hot) with 1/4 cup Tea Tree Oil,1/4 quarter cup Peppermint Soap, 1 tablespoon peroxide and 1 cup alcohol. Over spray the shit out of everything. This is effective at killing every type of mite there is, including eggs. Use weekly (or every 4-5 days if you have a bad infestation). Lights must be off and room/plants MUST be cool. Don't run room fans for a few hours, but exhaust fan is fine. When everything is dry, you can put you lights back on. Room will have a wonderful peppermint smell for a couple of days, plants will look terrific.........