HumidX Plus Use and cleaning

[sansnap]

I recently started using an Air Mini for travel. (Resmed 10 at home).  At home, I run the humidity high and have found the Mini is a bit drier than I like, even with the 'wetter' HumidX Plus.

2 questions:

1. After a few dry nights, I preloaded the cartridge with a few drops of water. It substantially improves the humidity levels, in use. Does this harm the cartridge in any way?
   
2. Over the past weekend, I camped in an area with forest fires and smokey air. Both the machine filter and the cartridge are noticeably discolored. There are only a few nights use on the 30-day cartridge.  Can this cartridge be cleaned? Does anyone know what it's made of?