hello. i have 4 male asian box turtles and one male red-eared slider. i need to increase the heat and humidity in a 9 X 13 area in my basement where they are kept. i have a clear plastic sheet curtaining off the area from the rest of the basement, a small electric heater running 24/7, an 8' x 2' cattle tub for the wet area with a fluval internal filter and a heater, a long wrap-around dry area made with plywood and indoor outdoor carpeting, and many lights. it is still too cold and not humid enough for the asian boxes. would adding a lot of potted plants help? what is a good way to increase the heat and humidity of a 9' x 13' area?