100% Biological Holding Tank Treatment in Dry Form. Our unique pellets are Certified Environmentally Safe. Combines both black and grey water treatments into one easy to use dry formula. Stops odours, digests waste, lubricates valves and is easy to store. No liquid to spill. Great for switching to a non-formalehyde treatment program. Crystal Blue will neutralize residual formaldehyde in your tank. Gets up to 15 treatments per jar. Economical and easy to use.