TST RV Grey Water Odor Control removes grease buildup in your grey water tank, sink and shower drains. This grey water holding tank deodorizer comes in a fresh lemon scent. Four ounces treats a 40-gallon holding tank. It is 100 percent biodegradable, does not contain formaldehyde, is environmentally safe and is non-staining. Product is safe for septic tanks. Color: Yellow; Model#: 40250; Brand: Camco