Unique’s Marine Digest-It is specially designed to eat odor and backups caused by solid waste and residual sludge inside the entirety of your holding tank system lines and all. Marine Digest-It works with salt water can be used in black gray and galley water tanks and cleans and maintains tank sensors as well as level gauges. Marine Digest-It dissolves all brands of toilet paper is formaldehyde-free and is proudly made in the USA. Disclaimer: Ingredient disclosures are to the best of our knowledge based upon information provided by our raw material suppliers.