PhosLock 795 gram phosphate removing media. P?RA PhosLock Professional Strength Phosphate Remover. PhosLock is the benchmark German made ferric hydroxide media for total phosphate removal in all aquaria. Used all over the world, it is the product of choice for many critical water purity applications. PhosLock permanently binds phosphates making them unavailable for feeding algae growth. With regular use of PhosLock any aquarium fresh or salt, reef or planted, will stay much cleaner, less maintenance labor intensive, and most important - algae free! Media bag with PhosLock can be placed inside of: canister filters, power filters, pond filters, sumps, refugiums, corner filters, next to uplift tube on UG filter plate. PhosLock can be placed directly into Bio-Bags or other fine floss bags. PhosLock is 5 to 10 times more effective than white activated alumna media and it is completely safe for fish and invertebrate, fresh and salt-water aquariums.