Picture of CO2 mixer for planted aquarium
I thought about effective CO2 mixing for a long time. I've tested almost everything: diffuser made from wood, air stone, glass diffuser, I've tested CO2 injected on canister filter inlet, etc.
First one is ok but you have to replace wooden airstone every ~2-3 months. Second and third solution is not effective at all. The last method is ok but some of the gas bubbles still going trough the filter and being wasted, bubbles which was not dissolved inside the filter flow out trough outlet pipe and gone, anyway at least is not elegant way.
I decided to make my own mixer from water filter housing.
Basically it's not my idea, and you can find plenty of similar solutions on Internet, but I'll try to describe how mine is made.

Step 1: General idea and overview

Picture of General idea and overview
Mixer is placed behind the canister filter, so water is coming trough filter than water seize the CO2 bubbles during the flow trough Tee connector on mixer inlet.
The mixer is made from in-line water filter housing. inside is handful of bioballs to make CO2 diffusion more effective.
The trickiest part of the job I've found, was to find proper connectors to filter to connect ordinary filter hose to mixer and connect CO2 on the inlet.
After nearly an hour of digging in B&Q plumbing department I've found plastic connectors for standard 15mm water pipe. When I removed nut from one end, I found the same 3/4 inch thread. Luckily, even better in terms of fitting/sealing, after the thread was a collar, so I was able to use rubber washer instead of sealing by normal Teflon tape or silicone sealant (you can see everything on the photos).
admin6 years ago
This is a great Instructable, but you need to add a main image of the final project to the intro step. Please do that and leave me a message when you have so that we can publish your work. Thanks!
72mpvet3 years ago
Really like the pictures; great resolution, point of view and helpful. Step one picture shows the electrical connections I’m not sure with my luck it would be a safe thing, any suggestions as to where to put the electrical strip? I’m building the tank stand.
crawshaws4 years ago
I think this is the link to the filter housing now. RS Seem to have changed it.

crawshaws4 years ago
Could you please tell me where you got your CO2 tank and regulator from please?
thewhite (author)  crawshaws4 years ago
CO2 bottles got from machinemart.co.uk (http://www.machinemart.co.uk/shop/product/details/co2-gas-cylinder-600g) the regulator is just a standard tetra setup. (I saw on ukaps.co.uk someone made diy regulator. if you'll register on ukaps.co.uk you can find it somwhere in diy section, hope that helps)
steed11726 years ago
this is great... i might use this after i get my 55gallon tank(i think 55) its big enough to NEED plants..lol great intructs keep it up now