Dehumidifier advice

I have a problem with musty odor in my 1960's ranch house in Atlanta. Atlanta is very humid, and my house has a lot of tree cover, making it extra damp. The top level of the house is at grade level, but the ground slopes, so the lower level of the house is partly below grade. Below the lower level is a dirt crawlspace which is fairly well sealed with plastic. The foundation vents of the crawlspace are also sealed, so it's pretty air tight.

I have a portable dehumidifier in the crawl space...

Dehumidifier advice