pureWash Pro is most effective at producing activated oxygen when the air it uses has low humidity, so it's important to replace your Desiccant Dryer Cartridge whenever the beads turn pink. Most users can expect to do this about once a year, but if your laundry room is exposed to non-conditioned air or if you have high humidity for other reasons, you might need to replace it even more frequently. Keep an eye on the window on the left of your pureWash Pro and order a new cartridge when it turns light purple. Even better, order a spare and always have your pureWash Pro working at maximum effectiveness. GreenTech Environmental innovates, develops, and manufactures high-quality electronic products that positively impact everyday the lives and health of people throughout the world - all while protecting the environment. Everything we do makes a difference. GreenTech Environmental stands for newest technologies created, distributed, and supported by an extraordinary group of people committed to providing you, our customers and consumers, lifelong service that amazes.