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fluval mini 20 co2

Fluval Mini Pressurized 20g CO2 Kit Review

For the aquarist with an average level of DIY knowledge, a co2 kit with everything you need in one single package can only be a good thing. The Fluval Mini 20g co2 kit is different to many other nano co2 systems because it uses a pressurised co2 canister to provide the gas.

Its RRP is £26.99 for which you get one 20 gram co2 cartridge, some tubing, a valve, a small bracket that holds the cartridge on the side of the aquarium and a bell diffuser.

fluval mini 20 co2

Once you’ve connected the system up, which takes a couple of minutes at most, the user must open the valve slightly to fill up the double bell diffuser. The co2 is pushed through the tubing, into the lower diffuser which then overflows into the upper bell. You then shut off the valve once both bells have been filled.

The co2 is diffused into the aquarium fairly slowly depending on the rate of flow past the diffuser unit.

Co2 cartridge

The cartridges themselves contain 20 grams of compressed co2 which provides enough for you to refill the diffuser 55 times. Most users seem to refill their diffuser 3 to 4 times daily meaning each cartridge would last around two weeks. You can buy replacement cartridges with a RRP of £14.99 for a pack of three.  [sws_pullquote_right]At this rate, it would cost you over £100 per year to run this system! [/sws_pullquote_right] With that you could buy a larger co2 system that’s cheaper to run long-term. On the other hand, some people have used 16 gram bike tyre co2 cartridges which they find to be compatible with the Fluval valve – you can pick these up in a bike shop for less than £1 per cartridge if you buy in larger packs!

fluval mini co2 cartridge

Cartridge Holder and valve

The cartridge holder is a nifty yet simple device that allows the cartridge to be hung just below the rim of the tank.

The valve seems fairly sturdy and well built. The adjusting knob is large enough for you to get a good grip and the co2 tubing is held nicely in place with a compression nut.


The diffuser is 100% efficient as the only way for the gas to escape from the double bell diffuser is for it to dissolve into the water. Unfortunately, this efficiency comes at the expense of both speed and size: The diffuser would unable to keep up with the co2 demands of a heavily planted nano tank and, measuring roughly 14 x 6 x 6cm, it takes up a lot of space too. The suckers aren’t fantastic and can come undone from time to time.

The diffuser cannot easily be replaced by, say, a ceramic diffuser as the co2 tubing Fluval provides with this kit is unable to withstand pressure.

fluval co2 diffuser


Whilst a very cheap set to buy, it can work out fairly pricey in the long run. The diffuser certainly isn’t the best but it is efficient. Overall, it is a decent setup if you have a small planted tank, but for a heavily planted tank it works out very expensive.

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