If I metal build a box 6 ft x 6ft x 3inches in height and create a metal roof similar to a house, allowing air to flow thought the soffit and out a vent in the middle of the roof. I was thinking a whirlybird Turbine vent. The roof would be only 1 inches above the box and would be flat to slightly tapered to the middle the turbine would be in the midle of the roof. I would completely paint it black and add 2 inches of water to the box. A small 12 inch diameter turbine vent with a constant wind speed of 5 miles per hour (mph) can remove 347 cubic feet of air per minute (cfm) through the box. Approximately how long would it take to evaporate all the water if the temperature was 75 degrees the humidity was 70%.