I recently built an evaporative cooler in my Nepenthes tank that I have been surprisingly pleased with. It gets the nighttime temperature drops that I need for highland and intermediate species. Below is a picture of the setup. I essentially use a reservoir located inside the tank with a humidifer pad that wicks the water up as it evaporates, and a computer fan to force dry air from the room over the pad and into the tank. There is a gap in the lid on the other end of the tank that allows for the humid air to escape, allowing for good airflow over the pad and through the tank. One problem that has cropped up after about a week is the not completely unexpected issue of mold on the filter. I also noticed a pitcher on one of my plants that suddenly blackened overnight with what appears to be the same mold. Because the filter acts as a wick and sits in the water in the reservoir inside the tank, there is little drying in between times when the fan is on. I've thought up two potential solutions for this, but I would like some input first before trying them. Ideally, I would use some sort of synthetic wicking material (e.g. not cellulose based) to reduce the amount of mold that can grow directly on the pad, although I am unsure about what sort of material this would be exactly. Alternatively, I was considering using some sort of sterilizing agent in the water reservoir to control mold growth on the pad. I do have access to Clearys 3336, and had also considered just using household bleach in the water, although I am unsure of whether this could impact the plants in some way. Have any of you dealt with these kinds of issues before or are there any recommendations? As always, thank you for your advice and expertise. It is greatly appreciated!