Tried & tested

GEAR

FLUVAL BIOCO2 PRO 250

Reviewed by: Nathan Hill

RRP: £199.99 More info: https://fluvalaquatics.com/uk/shop/product/bio-co2-pr

Meet the Fluval BioCO2 Pro. Rather than rely on expensive, high-pressure pre-filled canisters of carbon dioxide, it instead utilises natural fermentation—in this case, yeast and sugar. That’s not a new concept; Fluval made a much smaller, plastic, uncontrollable, and much less attractive version of these some 20 years ago, before CO2 had really taken off, though at that time it was largely viewed as a novelty rather than serious kit.

This newer design is less about novelty and more about form and function. With sleek looks—either accidentally or by design, the BioCO2 Pro has a distinct ‘ADA luxury’ look about it—and a capacity that laughs at its earlier iteration, this is a product aimed at the aspiring aquascaper.

Out of the box, you get the main reactor with its screw-on lid and a regulator (a valve) on the top of the lid. There’s also a bubble counter which needs to be part filled with fluid and screwed on to the regulator. A length of airline is included, along with an in-tank diffuser (plus suckers), a non-return valve, and there are the necessary packs of activator (yeast) and CO2 booster (I’m thinking baking soda) to get everything started. Inside the bubble counter you’ll also find a spare gasket for the connection between the regulator and counter. It’s tiny, so keep it somewhere safe.

All that you don’t get in the pack is sugar—the necessary fuel for the yeast to work on—and some water.

Assembly and activation are reassuringly simple. Screw on the bubble counter, attach the airline (a threaded union holds it in place) connect the diffuser to the airline and sucker it into the tank, and leave for 24 hours to let the diffuser soak. Both packs of activator and both CO2 boosters then go into the canister (the lid simply unscrews for this), 500g of sugar join them, and then you fill to the fill line (marked inside the canister near the top) with room temperature water. Screw the lid back on, and 24 hours later you’ll see the start of your CO2 supply. You can now control the flow of gas via the regulator to measure how much gas is being delivered through the bubble counter.

Because there’s no solenoid, you need to turn the regulator on and off daily (excess CO2 overnight in a planted tank can be let