Product performance review needed - Boyu External Co2 Diffuser

oregon aqua

Junior Poster
Sep 14, 2008
West Linn Oregon
I have used it and i liked it.

Pro: It is simple gets pretty good small bubbles, and easy to clean, also does not cause loss of flow like a inline reactor or mazzi can.

Con: Its not as effective as some diy reactors and can cause gas buildup in the filter.
I think its as good as my glass diffuser in Co2 diffusion performance, I have nothing to base this on but my observations of the fish and plants.

I would still be using it but i broke off the Co2 inlet, dont know if i played with it too much or it was brittle from Co2. I chalk it up to a con though.


Guru Class Expert
Feb 17, 2007
Lincoln, UK
oregon aqua;28849 said:
Con: Its not as effective as some diy reactors and can cause gas buildup in the filter.

Lol it is supposed to go on the filter outlet side not the inlet!!! therefore the gas goes away from the filter and not into it!!!

Peter Kirwan used this on one of his prize winning 'mountainscape' tanks this year.

I have 2 but I don't use them at the moment. They can be awesome or terrible dependent on the way you use them.

They can be attached via a bit of hose under a powerhead and that works well but looks ugly. The strainer cup goes on the 'intake' side in this case.

They can be attached to a powerhead outlet which works OK but again ugly.

They can be attached inline on the output side of the filter which either works brilliantly or terribly dependent on your attachments. If you have Lily pipes close to the surface then you are injecting very close to the surface and therefore lose a lot of the CO2. Peter Kirwan use on of the ADA jetpipes which worked very well.

The final way they can be used is by putting them on the end of the filter attatchment within the tank and this works well but will blow the substrate around a bit if you have it too close to it.

A few pics:

This is on the outlet side of the filter. which is the same way as Peter Kirwan used his. Worked well with his ADA jet pipe. didn't work well with my Lily pipe. Peter went to a jet pipe after seeing it didn't work with his Lily pipe.

This is a hort video of the unit in use under a powerhead within the tank.

Then I tried to hide it a little at the back:

In the end I bought a Koralia and aimed it at the glass/disc diffuser which worked very well and that is how it remains to this day. lol

I still have the Boyus though. they may be useful for a future scape/equipment.



Jan 24, 2005
Cologne, Germany
A somewhat related question here: I'm still looking for an easy way to inject oxygen efficiently into water without using ugly devices inside tanks. Has anyone tried the Boyu for oxygen distribution? Might this work or will the back pressure be too high for an ordinary 02 pump?

Best regards,


Guru Class Expert
Oct 25, 2006
Boyu external co2 diffuser

Where are you guys sourcing this from, i would be willing to give it a try.