Star brite Instant Fresh Toilet Treatment controls holding tank odors and gassing. It also keeps holding tank walls and drain lines free from debris while lubricants prevent drain valves from sticking. Ideal for all RV, marine, and portable toilets. The formaldehyde-free formula can be pumped out at any dumping station. Features Lubricates drain valves Breaks down waste & tissue Formaldehyde-Free Fresh Pine Scent Directions HOLDING TANK SYSTEMS:. Black Water: Use 1 fl. Oz. For each 5 gallons of tank capacity. Pour through toilet into holding tank and add 1 gallon of water. Hot weather and long retention times may require additional treatment. Grey Water: Use 1 fl. Oz. For each 10 gallons of tank capacity. Pour through shower or sink drain and add 1 gallon of water. RECIRCULATION TOILETS:. Pour 8 fl. Oz. Into initial water charge. PORTABLE TOILETS: Pour 4 fl. Oz. Into waste holding tank with enough fresh water to cover tank bottom. 8 oz: Treats up to 40 Gallons. 32 oz: Treats up to 160