One thing to consider is it isn't so much the humidity that is the problem. It is between 50 and 100% humidity in Louisiana where I lived 100% of the time. You need to create airflow more than anything. Just think of the mildew the same as Cyano in your tank. More water flow, less cyano issues. As I said before, with the humidity we had down south, between central air and a couple fans moving air, the only mildew/mold problems we had is where air cannot flow, i.e. dresser drawers and closets. The bathrooms are difficult as well, my wife was on it with Tilex bathroom cleaner and we wiped problem areas down every day or so to keep condensation from accumulating, in addition to plenty of air flow. It is a pain and it sucks, but just think, at least we in CO don't have to worry about algae and moss growing on the siding of our house! My tan house in LA turned green if I didn't spray it off every week or 2. Another story though!
Bill