like i said above it is strange but i never have any mold problems. i wonder if the caf trays you are using are creating mold. the two things that create mold are standing water and heat. with no drainage there is bound to be standing water in those trays. i would switch to something with drainage and see if that helps with the mold. you can get 5 reusable trays for $7 at SSKI ts.com">http://www.wheatgra SSKI ts.com just make sure they are the ones with the holes in the bottom. that same website also sells a mold retardant based on grapefruit juice, you might want to give that a try too if the H2O2 (Hydrogen-Peroxid) doesn't work well enough.
i would be interested in hearing other people's mold issues though.