Mold problems with evaporative cooler pad holders

Hi,
I live in Tucson, AZ and I have a tradewinds 3 sided downdraft evaporative cooler. I set up my swamp in May, with new pads a clean tray, one of those cooler cakes, and new inline water filter, and in addition to the pump I bought a Master Clean (or something like it), and I am still having mold issues. Every season I start to get mold growing on the pad holders.

So I spent the better part of Saturday afternoon scraping the holders and I replaced the pad and water in the tray.

Is there any water additive to help prevent the mold? Or do I just need to replace the filters more often?

 

Hi, I had that problem with aspen pads. i got rid of them and got the green pads and had no more problems.i found a trick out put your cooler on low vent for about a half hour before shutting down it will dry the pads out.