Bio-CO2 Pro

Fluval Bio-CO2 Pro combines the safety of biological carbon dioxide production with the convenience of pressurized delivery. With reliable, controllable, low-pressure operation, it is the most secure, simple and environmentally sustainable CO2 delivery system available.

Fluval Bio-CO2 Pro operates at a lower – and therefore safer – pressure than citric acid systems, and functions via a natural, environmentally-friendly biological process as opposed to a chemical reaction with hazardous ingredients.

Yes! Activated carbon can remove trapped gasses, including carbon dioxide.

It’s important to wait 24 hours after adding the ingredients to your Bio-CO2 Pro system in order to allow the fermentation reaction to occur, which increases the pressure inside the reaction chamber and allows CO2 to reach your aquarium.

Bio-CO2 Pro 125: add 1 cup / 240 g of table sugar
Bio-CO2 Pro 250: add 2 cups / 480 g of table sugar
Bio-CO2 Pro 500: add 4 cups / 960 g of table sugar
Note that a Bio-CO2 Refill Pack holds exactly one cup of table sugar.

For best results, add tap water with a temperature of 80-85°F / 27-30°C.

It does! For best results, the room temperature should be between 68-72°F / 20-22°C.

Bio-CO2 Pro 125: add 1 Activator yeast sachet and 1 Booster tablet
Bio-CO2 Pro 250: add 2 Activator yeast sachets and 2 Booster tablets
Bio-CO2 Pro 500: add 4 Activator yeast sachets and 4 Booster tablets

We do not recommend overdosing your Bio-CO2 Pro system. Doing so will result in a more intense reaction which could cause the reaction chamber to overflow. The quantities of each ingredient have been carefully measured to ensure effective and long-lasting CO2 production, and should therefore be adhered to.

Bio-CO2 Pro Activator yeast is professionally crafted for rapid-start fermentation and maximum CO2 production. We do not recommend the use of other types of yeast.

Bio-CO2 Pro Activator yeast sachets are air-tight and aluminum-lined for consistent quality and storage for up to 3 years.

Bio-CO2 Pro Booster tablets are made of dextrose sugar, which kickstarts the fermentation process.

We recommend starting with the following bubble counts and making adjustments to suit your particular aquarium:
Bio-CO2 Pro 125: 12 bubbles / minute
Bio-CO2 Pro 250: 24 bubbles / minute
Bio-CO2 Pro 500: 48 bubbles / minute
The CO2 Indicator Set (Item #17561) conveniently mounts to the aquarium glass and monitors carbon dioxide levels in the water to help you in this process.

We only recommend using tap water to fill the bubble counter.

Bio-CO2 Pro systems produce carbon dioxide for up to 30 days. Please note that ambient room temperature impacts the rate of CO2 production.

It’s possible the bubble count was too high or an improper quantity of water or table sugar was used. Ensure the water and table sugar are added to the reaction chamber first and are well mixed before the Booster tablet and Activator yeast are introduced. The ambient room temperature also plays a role and can dramatically extend or shorten the CO2 production time.

Be sure to add the water and table sugar to the reaction chamber first, and mix them thoroughly before introducing the Booster tablet and Activator yeast. Verify that the check valve is installed in the correct orientation, with the black side facing the diffuser. Check that the bubble counter gasket is installed correctly, and that both the bubble counter and the diffuser are filled with water. Ensure the tap water is warm enough – we recommend temperatures between 80-85°F / 27-30°C. It’s possible the ambient room temperature is too low: if it’s not within the recommended range of 68-72°F / 20-22°C, try raising the temperature, or position the Bio-CO2 Pro system inside the aquarium cabinet, next to the canister filter, to help keep it warm. Lastly, close the regulator and allow the system to continue building pressure for another 24 hours.

Before adding new Activator yeast sachets and Booster tablets to your Bio-CO2 Pro system, empty the interior contents down a drain, thoroughly rinse out the reaction chamber and dry it using a soft cloth. We do not recommend the use of soaps or detergents.

Bio-CO2 Pro systems are designed to produce a slow, steady flow of carbon dioxide, ensuring your aquatic plants receive a continuous supply of this essential gas even when the aquarium lights are turned off. The production rate is calibrated to about 10 bubbles per minute per 25 US Gal / 100 L of aquarium volume – sufficient for the needs of your plants, while remaining safe for your fish, even overnight. Extensive testing involving multiple units operating nonstop over long periods of time has resulted in enhanced live plant growth and no adverse effects on fish.  

We recommend turning the system on an hour before the lights come on and turning it off an hour before they shut off. The Bio-CO2 Pro 500 includes a solenoid valve to facilitate this process.

Yes! Solenoid valves can be added to Bio-CO2 Pro 125 and 250 systems.

The solenoid valve on the Bio-CO2 Pro 500 is compatible with all mechanical and digital timers.

No. The regulator is specifically designed for low-pressure CO2 systems like Bio-CO2 Pro. Other regulators will not function as expected.

The CO2 airline tubing is made of polyurethane with a gas barrier.

Yes. We recommend measuring and cutting the CO2 airline tubing so that it follows a straight path from the bubble counter to the aquarium edge with no kinks, loops or excess.

No, the positioning of a Bio-CO2 Pro system relative to the aquarium has no impact on its performance. However, ensure the CO2 airline tubing follows a straight path from the bubble counter to the aquarium edge with no kinks, loops or excess.

The inline check valve should be installed with the black side facing away from the Bio-CO2 Pro system, towards the aquarium edge.

The inline check valve should be installed about halfway between the bubble counter and the edge of the aquarium.

Fully open the precision regulator to completely exhaust the CO2 supply and facilitate the opening of the reaction chamber lid. In the case of the Bio-CO2 Pro 500, the pressure release valve can be pressed to achieve the same results.

The pressure release valve automatically maintains the ideal pressure levels inside the reaction chamber in order to facilitate the fermentation process.

We recommend using a CO2 Indicator Set (Item #17561), which conveniently mounts to the aquarium glass and monitors carbon dioxide levels in the water.

The nano bubble diffuser should be positioned in the path of water flow within the bottom half of the aquarium, so the CO2 spends as long as possible in the water column to maximize plant uptake.

Routine replacement of CO2 diffusers is necessary every few months to maintain optimal carbon dioxide delivery.

Yes, new ceramic CO2 diffuser discs can take up to a week to begin emitting CO2 in a fine mist. It’s normal to see larger bubbles for the first few days of operation.

Bio-CO2 Pro systems are only intended for use in ornamental household aquariums.