QuickBlue from Safe-T-Fresh is a dual-film, effervescent deodorizer packet that dissolves in brine. It is manufactured by combining a PVA film with paper. The paper film dissolves much faster in water than PVC and is accelerated by the effervescent action, which also disperses the deep-blue color more evenly in the tank. The Event & Winter blend is designed for winter service. 888-556-4067; www.safetfresh.com.