Fluval Cycle Aquarium Treatment 2LtrFrom the Fluval range, Cycle Biological Enhancer immediately establishes a safe and stable biological environment in your aquarium. Its powerful formula quickly eliminates ammonia and nitrite, helping to prevent fish loss and allowing for the immediate introduction of fish. Safe for both freshwater and saltwater setups, it supports the rapid development of beneficial bacteria for long term stability. Supplied in a 2L bottle, it treats up to 4,000 US