Ammonia poisoning is the most common killer of aquarium fish. Ammonia is produced by decomposing plants, algae, fish waste, and uneaten food. Dangerous ammonia levels often occur in new aquariums or in an established tank when adding new livestock, when a filter stops working due to power or mechanical failure, or if existing beneficial bacterial colonies are lost due to the use of medications or sudden change in water conditions. Fritz A.C.C.R. will not alter pH or deplete oxygen levels. Fritz A.C.C.R. is a true complete water conditioner that not only neutralizes toxic ammonia but also the chlorine & chloramines found in tap water. Fritz A.C.C.R. Is extremely safe even when overdosed.