# DIY inline CO2 diffuser



## James Marshall (22 Jul 2009)

Here are the plans for the inline CO2 diffuser I recently built










In practise the design seems fairly effective, and is more efficient at dissolving and distributing CO2 than other diffusers I have used.
The design does not differ greatly from some of the DIY diffusers I have seen. However, it is simple to construct with no drilling, sawing or gluing required, and it improves contact time between water and bubble by spinning the water inside the reaction chamber. The spinning effect is produced by inserting an Eheim lock nut into the hose (as shown in the diagram). After an about an hour of running, the internal screw thread of the lock nut will create a small vortex , not  the raging vortex of terror I had hoped for, but it does increase contact time.
For my 20 litre tank a reaction chamber length of 25cm is sufficient, for larger systems simply increase the length.
I hope this is useful

Regards James


----------



## zig (22 Jul 2009)

Very good idea mate, so simple, the addition of the locking nut is basically giving you a quasi mazzei effect, I'd say you could improve upon it by using step down reducers either side of the Reducing T Piece, a simple idea would be to use hose pipe of gradually reducing smaller sizes pushed inside the 19mm eheim hose you are already using that should create the vortex more effectively (I think), it would reduce your flow obviously but maybe not that much, your idea is so simple you could play around with it very easily. I will give you 9 out of 10    overall simple effective idea.


----------



## James Marshall (22 Jul 2009)

Thanks Peter

I see what you mean about the step downs i may give that a try.
I think that the pitch and depth of the thread in the lock nut are too small for ideal effectiveness.
At conception, I wanted to use the top section of an Eheim surface skimmer ( as this creates a very  effective vortex, to keep suction constant within the skimmer unit), but at 35mm diameter I could not find hose and fittings to match.
I'm currently looking at impellor covers, as some of these have angled fins internaly, which may improve things.

Cheers James


----------

