The basic principle to follow is if yuo prevent the moisture from entering, you prevent the source of the problem instead of trying to deal with the symptoms. Hears a few suggestions: 1/If water is able to flow into the crawlspace, stop it. 2/ elimniate ground vapors (poly over the ground) Prevent humid outside air from entering. I usually suggest sealing any vents & insulating the perimeter, perhaps w/ foam board insulation. These are the main ways moisture enters a crawlspace. Solve those & you solve the problem.