Negative ion generators have been used for years now to cut down on odors
in a grow room, but reports are coming in that a negative ion generator will increase growth speed and yield. No true evidence to support this, however it does make sense, due to the fact that people and animals seem to be altered in
a positive way by negative ions in the air, so plants may "feel" better too. Try putting one in the grow room. You may notice the buds don't have as much
scent when picked, but that may be desirable in some cases.

A negative ion generator can be purchased for $15 to $100 depending on the
type and power involved. Some have reversed cycles that collect the dust to a charged plate.