Dometic Max Control-Natural Holding Tank Treatment eliminates odors and effectively breaks down waste in your sanitation holding tank without the use of formaldehyde or bronopol. The fast-acting proprietary enzyme/bacteria formula enhances beneficial bacteria and will continue to work and benefit downstream systems like septic or municipal treatment facilities. A light appealing fragrance means Max Control-Natural works for portable and gravity toilets and can be used in black or gray water tanks. California compliant and approved for use throughout North America. Use 4 oz. liquid, per 40 gallon black or gray water tank treatment.