SeaChem Prime is the complete and concentrated conditioner for both fresh and salt water. Prime removes chlorine, chloramine and ammonia. Prime converts ammonia into a safe, non-toxic form that is readily removed by the tank's biofilter. Prime may be used during tank cycling to alleviate ammonia/nitrite toxicity. Prime detoxifies nitrite and nitrate, allowing the biofilter to more efficiently remove them. Prime also promotes the production and regeneration of the natural slime coat. Prime is non-acidic and will not impact pH. Prime will not overactivate skimmers. Use at start-up and whenever adding or replacing water. & A& 2 L bottle treats over 20,000 gallons, much more than competing products.Marine and freshwater.