I have a 200 gallon pond in basement. I do not have a humidity problem anymore. I put three glass panels across the top. I would strongly suggest a cover. One for jumping. Two for splashing. They jump and splash all day long. I hear them from upstairs. This creates a new problem. Water on the floor, walls, where ever it decides to land. I have two ID sharks 25" & 17" and a 22" Golden Clown Knife. They think they live at Marine Land. In the winter, with the furnace on, the humidity in the basement reads 20%. That's not bad. I do not have a mold problem. Which is another humidity issue. Good luck.