# DIY CO2 Diffuser ideas?



## joeyd71 (Aug 14, 2011)

I'll be making a DIY CO2 system, and I imagine I will need a way to diffuse the CO2 bubbles coming out. I don't live near a pet store, so buying a diffuser is out of the question. So I need to take the DIY route. I heard of using chopsticks, but would sticking any piece up wood up the line work? Any other ideas? I thought about using a sponge on the end.

Depending on how this works, I'll be using it on a larger scale on my bigger tanks. Figured I'd work out the kinks on an all plant tank first before I risk lives.

One last question- which would you consider more important- good substrate or higher CO2 level? I'm just not sure which problem I am having with my other tanks with trying to grow plants....whether or not my substrate sucks or I just have low CO2. I had a plant in my 29 gallon for about 2 weeks and when I pulled it out it had very little growth on the roots.

Thanks.


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## Summer (Oct 3, 2011)

You have a few options. 1. order one online 2. a chopstick made of bamboo shoved in the end will work and 3. this one you might think i'm nuts but i use it on my DIY setup, an unused cigarette filter shoved into the end of the hose. I get tons of fine misted bubbles from it.


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## joeyd71 (Aug 14, 2011)

Summer said:


> You have a few options. 1. order one online 2. a chopstick made of bamboo shoved in the end will work and 3. this one you might think i'm nuts but i use it on my DIY setup, an unused cigarette filter shoved into the end of the hose. I get tons of fine misted bubbles from it.


Well the whole buying it online thing won't work for me right now because I am doing it this weekend. I'll have to try to find some bamboo I guess then. Or.....come up with some other crafty way. I have airstones everywhere, but I assume they won't make small enough bubbles


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## Summer (Oct 3, 2011)

They wil work, but the finer the bubbles the better.


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## Cadiedid (Oct 26, 2011)

Joey-I've seen Summers cigarette filter in action and it really works! I'll be going this route myself!


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## DonD13 (Jan 5, 2012)

There are lots of DIY methods for diffusing CO2. The things that really make a difference are surface area (lots of small bubbles dissolve much faster than a single large bubble) and time of contact (how long the bubbles stay in the water without rising to the surface). 

I built my diffuser last week, and it is working great so far. I used 2 airstones at the bottom of an air-lift tube (like used for an undergravel filter). The airstones make pretty small bubbles, so lots of surface area. To increase the time of contact, I put a piece of 5/8" plastic tubing (like used for siphoning for water changes) in the middle, plugged with epoxy on one end to keep the bubbles from getting into the center. Then I wrapped a loose spiral of silicone air line around that larger 'core' which filled the space between the core and the outer air-lift tube and forces the bubbles to rise slowly around a long spiral path instead of rising straight to the top. Sounds complicated, but I threw it together in an hour and it works great.

Let us know what you end up building.

Don


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## Cadiedid (Oct 26, 2011)

DonD13 said:


> There are lots of DIY methods for diffusing CO2. The things that really make a difference are surface area (lots of small bubbles dissolve much faster than a single large bubble) and time of contact (how long the bubbles stay in the water without rising to the surface).
> 
> I built my diffuser last week, and it is working great so far. I used 2 airstones at the bottom of an air-lift tube (like used for an undergravel filter). The airstones make pretty small bubbles, so lots of surface area. To increase the time of contact, I put a piece of 5/8" plastic tubing (like used for siphoning for water changes) in the middle, plugged with epoxy on one end to keep the bubbles from getting into the center. Then I wrapped a loose spiral of silicone air line around that larger 'core' which filled the space between the core and the outer air-lift tube and forces the bubbles to rise slowly around a long spiral path instead of rising straight to the top. Sounds complicated, but I threw it together in an hour and it works great.
> 
> ...


Don, that is an awesome idea. Did you think of it yourself? How did you attach the top and bottom ends of the silicone air line to the central core? Do you have any photos?


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## Gizmo (Dec 6, 2010)

I've heard airstones in or under the filter outlet work as well...


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## FishFlow (Sep 13, 2011)

What equipment are you working with ? Additional ideas.

If you have a power head, feeding the air into the intake of a powerhead can chop up into fine bubbles.

If you have a canister (or something that pumps water through a tube), create a reaction chamber (difusion chamber) I just created one of these with pvc from hardward store and is working great. Although I decided to get brass check valve (online) to replace the air hose barb.


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## snail (Aug 6, 2010)

Summer said:


> this one you might think i'm nuts but i use it on my DIY setup, an unused cigarette filter shoved into the end of the hose. I get tons of fine misted bubbles from it.


Lol, first positive reason for smoking I've heard.

Some great ideas here though, a useful thread.


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## dclark61 (Jan 21, 2012)

Although not as good as having fine bubbles, anything that can maximize the time that the CO2 spends in the water will work.

When I had a planted tank, I had a DIY setup consisting of half-gallon soda bottle containing sugar/yeast mix, cork on top, airline with check valve (I'm sure you know of this setup), with the airline feeding bubbles into a plastic device I bought online (I forget where) that was basically a ramp which the bubbles would travel up, getting smaller as they slowly traveled up the ramp and partially dissolved into the water. Like this:

/
\
/
\
/
\ <== airline connected here

Of course the ramped parts weren't steep than that. 

I think building something like that would be fairly easy. Try to keep the ramps not too steep, but steep enough that the bubbles do slide up.

Or anything like that that keeps CO2 exposed to the water as long as possible. I think some people have used the equivalent of inverted plates/bowls.

Have fun.


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## DonD13 (Jan 5, 2012)

Cadiedid said:


> Don, that is an awesome idea. Did you think of it yourself? How did you attach the top and bottom ends of the silicone air line to the central core? Do you have any photos?


Here's a quick photo:



This is rotated 90 degrees to fit into the camera frame. It is actually vertical as you would expect.

Definitely room for improvement, but works pretty well. 

To answer your question, the silicone line is not currently attached to the 'core' at all. I will pull it out next water change and make a few improvements, primarily correcting the twist rate by gluing each wrap to the core with super glue. Currently the small bubbles get caught on some of the almost horizontal wraps of the silicone line, build up into larger ones, then progress further up the spiral. Ideally, they would stay small and slowly make their way up until they totally dissolve. The big external loop at the top is because the white (originally clear) line passes out of the front of the air-lift tube's grating because the top air opening has a second (black) silicone line passing through the middle of the core to a second air-stone. The bottom of the core is plugged with marine epoxy to prevent bubbles taking the short route straight up the core to the top. 

I'll take some more pictures and post them when I pull it and re-assemble it. 

Don


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