Also if you look on ebay, acrylic is very cheap, I've been thinking about doing something similar. Theres tower evaporators, and theres high surface area evaporators. I want to combine them with the magical properties of acrylic!
A 4-5" diameter acrylic pipe, inside that a ton of 1/4" acrylic pipes with a bit of room between em, water flows up thru a center 1/2" pipe, fills a top resevoir of sorts, which has anchors for the 1/4" pipes, but lets water dribble down the outsides of those, then fans would blow across that creating a huge surface area for evaporation. Plus acrylic would "hold" the water in place pretty well so it would probably create quite a lot of evaporation!
Dehumidifier will help if it doesnt get overloaded. My main suggestion is, run a pipe from the top to the outside world with a fan in it. Yes the outside world, don't be afraid, they've removed most of the pointy objects and bright sun light from there so I hear!