Valterra - Odorlos Holding Tank Treatment - 68 oz. Bottle- V77003. When added to holding tanks, Odorlos provides the naturally occurring bacteria with a continuous supply of the best alternative energy source to pure oxygen - nitrates. This eliminates the need for bacteria to target sulfate for energy, and the result is no holding tank odors.. Features:. Size - 68 oz.. Self-Measuring Bottle. Tip to measure the perfect amount every time. Safe and effective in all RV and marine holding tank and septic tank systems. One ounce for every 10 gallons is all you need. Effective even in extreme temperatures. Accelerates the breakdown of tissue and waste, helping to prevent clogs. Scent-free formulation. 100% biodegradable/eco-friendly, formaldehyde free and non-toxic