FritzZyme 7 contains live freshwater-specific strains of live nitrifying bacteria proven to reduce fish loss due to toxic levels of ammonia and nitrite. Nitrifying bacteria can take weeks to naturally establish colonies in new aquariums while ammonia and nitrite can reach lethal levels in only a few days. FritzZyme? 7 provides the proper balance of bacteria proven to rapidly seed biofilters; greatly reducing the natural cycle time allowing for safe and faster addition of livestock. FritzZyme 7 may be added to new tanks or established systems any time the biofilter needs fortification including: after water changes; aggressive cleaning; adding new livestock; medicating or changing filter media. FR80207 Casebuy:12.