A blend of phosphoric acid and certain suspending agents, this acidic cleaner will expedite the removal of scale, oxides, concretions, and other stubborn contaminants from inside STEEL dive tanks. It's biodegradable and can be flushed down drain systems without harm. It has FDS, USDA, CDA, CDF approval and also meets many mil-spec requirements. The acid concentrate, when diluted to 5 - 10% strength for use, will speed the process so that only 1-3 hours will be required for completion. NOTE: Use this cleaner on STEEL TANKS ONLY: acids will attack aluminum models! See Bulletin #42130 for additional information. Ships HAMAT at additional cost.