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Glass Co2 Diffuser Review

glass-co2 DESCRIPTION:
Highly efficient glass CO2 diffusers optimize carbon dioxide supplementation in planted aquariums. Specially designed to maximize contact time between carbon dioxide and aquarium water. Ceramic diffusion plate dissolves 90% of CO2 that pass through it. For use with most CO2 systems.

If you have been shopping online for a new Co2 diffuser, you probably know those fancy Co2 diffusers. They have invaded the market lately but are they good at all?
I use to sell all kinds of Co2 glass diffusers so I thought I could make this quick review for you guys.

They come in many shapes and sizes. Many stores gave them different names but just so you know, they are pretty much all the same. Some of the most popular models are certainly:

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Value For Money:
Build Quality:
Ease Of Use:
Overall rating:
Rating: 4.5/5 (3 votes cast)

glass-co2 This one is often call Spiro and comes in 3 different sizes.

co2diffuser2 Also very poppular, this flat and less fancy model comes in 3 different sizes.

co2diffuser3 And there is finally this cup-like diffuser. Also really poppular.

There is many other models available but I think those three are the most common.

Here is how it works (It’s realy simple!):
The Co2 is pushed through a ceramic diffusing disc (the white part on the diffusers) which creates tiny bubbles. Small bubbles allow maximum contact with the water. This actually why those diffuser are much better than our good old Co2 ladder which makes bigger bubbles (less contact with water, more waist).

How to chose a glass diffuser:
While shopping for a glass diffuser, you will notice a recommanded tank size for each models. Just so you know, this is all wrong. The size of the diffuser has nothing to do with Co2 diffusion. Only the diameter of the ceramic diffusing disk does. The wider it is, the better it is. Finally, they work best when placed low in the tank which allow more contact with the water (it takes more time for the Co2 to reach the surface).

So if we look at the first model above, there is no point in buying the two larger models because the ceramic disk is the same on all models. So if you chose to go with that one, save some money and go for the smaller one. Because it is shorter than the two other sizes, it will be easier to place it low in the tank.

The 2nd model above (the flat one) is what I think the best choice. It is not as nice but because of it’s shape, it will be easy to place it right next to the substrat for better Co2 diffusion. The biggest model is also wider than the others so diffusion will be much better. If you chose to go with that one, go with the biggest one.

The 3rd model above is a good choice for those looking for a good diffuser at low cost. However, the ceramic disk is smaller so I would not recommend it for large tanks.

The cost of a Co2 glass diffuser:
Just so you know, when buying them at wholesale, they don’t worth much more than $2.50 each (sometime less than that). All that to say that you will pay for the brand name more than the diffuser itself. So try to stay away from big brand name such as ADA (I would like to say hi to Takashi Amano from ADA. Your tanks look great!).

Finally, they look nice but ship really bad. According to my experiences, one out of ten will break during shipping so ask the seller about his shipping and refund policy before buying.

I have been using those diffuser for the last 3 years with great succes (I use the flat one).

Please excuse the music on that video:

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Comments (4)


  1. Wally says:

    Hi there, thanks for the review, I am just curious, does this type of diffuser work well for DIY bottle CO2 systems?

  2. admin says:

    I have not tried them with yeast Co2 systems but I now may people are using them this way.

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