Viper Pan & Drain Treatment 1-gal is a triple-action gel that cleans, deodorizes, and prevents buildup in HVAC drain pans and lines. Enzymes break down sludge and slime, while silicone leaves a non-stick coating that keeps water flowing. Unlike tablets or strips, which dissolve quickly and fail to remove existing buildup, Viper Pan & Drain’s thick gel clings to surfaces and continues working for up to 90 days.