Fluval Biological Enhancer (sold overseas as Cycle) is a live bacterial supplement that seeds an aquarium with the beneficial bacteria which eliminate toxic ammonia and nitrite. It is what you reach for when setting up a new tank, adding fish or replacing filter media, in fresh or saltwater. It is a living product rather than a chemical, which sets two limits: Fluval says the bacteria will have died if the bottle has ever been frozen, and a single dose is not a fix — plan on dosing weekly.
Shake before each use; the small beige particles are the Bio-Floc carrier that keeps the culture stable in the bottle, not sediment. Fluval states it is impossible to overdose, so at minimum dose for the amount of water changed. The only way to know it is working is to measure — pair it with the Fluval Aquarium Test Kit and watch ammonia and nitrite fall.
Features
- Eliminates ammonia and nitrite — releases beneficial bacteria that metabolise both.
- Immediate inoculation — the bacteria are dormant in the bottle and activate quickly once dosed.
- Bio-Floc technology — the carrier that keeps the culture viable in storage.
- Cannot be overdosed — Fluval states fish are not put at risk by a heavy dose.
- Fresh and saltwater — the same product for both.
- Pump top on the 2 L — each pump of the 2 L nozzle dispenses 5 mL.
Specifications
- Use — freshwater and saltwater aquariums
- 120 mL treats — up to 908 litres (240 US gallons)
- 250 mL treats — up to 1,892 litres (500 US gallons)
- 2 L treats — up to 15,140 litres (4,000 US gallons)
- Dose frequency — weekly minimum, and with every water change or filter media change
- Storage — do not freeze; avoid high temperatures
