K.E.
I have a Crane Penguin humidifier, and I use a Protec Cleaning cartridge. I get them at Wal-Mart and they last about 3 weeks each. They are about 3 dollars each. It is a little ball that you drop in that has beads. It keeps the water from getting slimy by inhibiting the bacteria and mold growth. They are located on the top shelf near the pharmacy, near the humidifiers I think. Hope that helps!