I am not familiar with your system, but in mine I rinse the trays in my kitchen sink twice a day. I don't have a system where the water goes into the top trays and runs through the lower trays. Mine are just flat trays on a shelf in my laundry room. I have only discovered mold if I didn't rinse them often enough, like if I missed an evening rinse. Maybe you need to rinse with cool fresh water more often if its too warm in your home and creating mold.