Fluval Cycle Biological Enhancer for Aquariums, 250 ml

Inoculates water with a powerful team of beneficial bacteria to jump-start the nitrogen cycle.

Helps eliminate ammonia and nitrite, promoting a safer environment for fish and invertebrates.

Safe for both freshwater and saltwater aquariums, covering versatile use cases.

Useful during water changes and filter media changes when beneficial bacteria are depleted.

250 ml bottle treats aquariums up to 500 US gallons, offering strong coverage for medium to large setups.

Simple liquid dosing format that integrates into regular aquarium maintenance.

Trusted Fluval brand with a long history of reliable aquarium care products.

Label guidance to stock fish immediately after dosing can be misleading for beginners.

Effectiveness depends on correct dosing; misapplication reduces benefits.

For very large tanks, a single 250 ml bottle may not sustain the cycle without refills.

Results vary by tank conditions and existing biological load; it is not a guaranteed fix.

It does not replace ongoing water-parameter monitoring and proper cycling practices.