# DIY CO2 System - How to do it



## Hoppy (Dec 24, 2005)

The CO2 diffuser will be an internal filter, a Cascade 300, that I have had for a few years.









It has two filter chambers separated by dividers with small slits for water passages.









The CO2 will bubble through a check valve in the lowest chamber, through tiny slits, which will reduce the bubble sizes through another chamber and through more slits, to the powerhead rotor, which I modified per a Tom Barr method.








I used nail clippers go split each paddle into two thinner paddles, then slightly bent them to misalign them. This makes the rotor act similar to a needlewheel rotor, further chopping the bubbles into very tiny ones, without much affecting the flow rate.

Since this will be vertical in the tank, the CO2 will all float up, with none of it escaping the rotor. With the check valve inside the filter chamber, there should be no water migrating back down to the bubble counter, a usual problem with CO2 systems.

This is for a 65 gallon tank, not an easy one to get a good CO2 level in with DIY, so I want a good diffusing method, even at the cost of having CO2 mist in the water. I'm doing this because I use low light, about 30 micromols of PAR, and my plants grow too slowly, and not reliably enough to suit me, but I like the absence of algae problems too much to increase the lighting. This should give me enough CO2 to improve the plant growth even though it isn't at all likely to come close to 30 ppm.

Now if I can just get the check valves.


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## Gplus (Apr 2, 2012)

Awesome write up Hoppy! I might have to pull out my old penguin 550 powerhead and try that " half ass needle wheel" trick! Really neat and creative stuff.


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## Hoppy (Dec 24, 2005)

Gplus said:


> Awesome write up Hoppy! I might have to pull out my old penguin 550 powerhead and try that " half ass needle wheel" trick! Really neat and creative stuff.


I don't get credit for this - Plantbrain originated this modification and tested it out. I'm just finally finding a use for it.

My check valves finally showed up today.








One check valve, allowing flow out of the bottle, for each bottle









One check valve in the internal filter, allowing flow into the powerhead portion.

I bought 4 of them, so I'm using the fourth one as a connector for the tube from the bubble counter to the tube into the diffuser (internal filter). Hopefully, I will get this set-up in the tank this evening. Timely, because I just planted some more stem plant cuttings.


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## Hoppy (Dec 24, 2005)

It is installed now! Unfortunately, I didn't have as much sugar as I thought, so I ended up with 2/3 sugar 1/3 Karo syrup. My proportions are 1 1/2 cup sugar/syrup, 1/2 tsp bread machine yeast, 1/2 tsp baking soda, in 2 liters of water, roughly - up to the end of the cylindrical part of the bottle and a half inch higher. I soaked the yeast in slightly warmed water, then poured it into the water/sugar/baking soda mix, and topped off the water.


















The diffuser is low, at the back of the tank, with the water flow aimed to graze the back of the tank, so it doesn't blow down the stem plants. No CO2 bubbles yet, of course. That will take a few hours to stabilize, and a few more hours to remove the air in the system.


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## driftwoodhunter (Jul 1, 2011)

I have never seen this before (I don't know a thing about Co2) but your step-by-step pics and descriptions are fantastic - I have confidence that even I could do this now! 
Thanks Hoppy!


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## sewingalot (Oct 12, 2008)

Nice setup, Hoppy! I like how you used black tubing rather than the clear. Is it much more expensive? I've never seen it in our LFS.


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## AaronMB (May 9, 2012)

Nice write up, Hoppy. Thanks.

Thinking about it now--for those of us with an ol' HOB sitting in the cabinet--I wonder if using a small HOB filter, just for CO2, would be useful (as opposed to the simple tubing and chopstick I'm currently using for my DIY CO2). Do you think the gas exchange as the water flowed from the filter and back into the tank would nullify some of the CO2 that was initially injected into the HOB? (EDIT: this was a sudden thought and I haven't searched on it.)

I tried placing the CO2 'diffuser' near the intake of my Fluval 206 but the filter housing collected the CO2 until it piled up and dumped large amounts into the tank every few minutes. Any fish in its path was noticeably put off by this! So... 

Sewingalot - I've seen black tubing at my local Pet* stores. It's priced about the same.


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## Hoppy (Dec 24, 2005)

sewingalot said:


> Nice setup, Hoppy! I like how you used black tubing rather than the clear. Is it much more expensive? I've never seen it in our LFS.


Oh Gee! I don't have my acceptance speech written yet

I got the tubing from a LFS near me, and it was available in 10 foot lengths, where the clear wasn't. Then I decided I liked the black color better too. It was $3 for 10 feet.

DIY CO2 is almost always on the low end of being enough to do much good, so I think it is worth the effort to find a way to make the diffusing process as efficient as you can. A HOB filter is likely to outgas a significant amount of the CO2 before it can be used by the plants, so I wouldn't try that. There used to be a very tiny cheap internal filter, the Elite by Hagen, sold only at Petco, that worked well as a diffuser, and was a very popular diffuser for a few years after a writeup on it in APC. I still have one of those also, but I wanted more water circulation in my tank so I decided to use the larger Cascade one I also had. Another efficient diffuser is the traditional external 2" PVC pipe method, but that requires a water pump or canister filter, and I'm not using that on this tank.


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## Hoppy (Dec 24, 2005)

16 hours later, and the bubble counter shows 1 bubble per second. The diffuser chirps loudly with each bubble going through, and that happens 2 times per second, so the idea of running the CO2 through the slitted filter chambers is chopping the bubbles into half size bubbles. All is working fine, but, as usual this is a somewhat noisy diffusing method.

The lights just came on. You can't see the bubbles! If you look very carefully you can see the haze of microscopic bubbles leaving the little internal filter in bursts. But, it takes a really good eye to spot the bubbles in the water - they really are microscopic. No champaign look at all. Now, this is true CO2 mist.


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## oldpunk78 (Nov 1, 2008)

I'm not sure if you've got the room or not but if you can fit an air stone in the filter, it will make a big difference in noise.


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## Hoppy (Dec 24, 2005)

An air stone was my first choice, but I found I don't have one. And, I wanted the check valve there to hide it. If my wife gets too upset about the constant chirping I will try the airstone. I could probably put it downstream of the check valve right where it is. Unfortunately they tend to disintegrate with CO2 going through them, in my experience. Maybe a really good quality one might last a long time.


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## shrimpNewbie (May 6, 2011)

Stick the end of a bamboo chopstick in it in place of air stone


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## Hoppy (Dec 24, 2005)

shrimpNewbie said:


> Stick the end of a bamboo chopstick in it in place of air stone


How long do those last before plugging up or disintegrating? I have some bamboo chopsticks, so the cost is about right.


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## Hoppy (Dec 24, 2005)

I found these, http://www.wayfair.com/Hagen-Elite-Mist-Air-Stone-A983-4-HGE1777.html at an LFS near me and bought a 3 pack of them, and installed one on the end of the check valve shown below









Now it makes a lot less noise, just an occasional slight click as a bigger bubble goes through, and the mist in the water is still very good.

After about 24 hours I can see an effect of the CO2. I have a little clump of Rotala cuttings that has just stayed alive, no growth for 2 months now. It is now green, with about 3/4 inch of new growth with bigger leaves. I expected this, having seen the effect on my last tank. I can't see any change in the other plants yet.


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## BS87 (Apr 9, 2012)

Do you plan on running any kind of drop checker or CO2 measuring device in the tank? or is that not of concern with DIY CO2?


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## Hoppy (Dec 24, 2005)

No, I haven't set up a drop checker. I know from experience that there won't be enough CO2 to harm the fish, and I won't be able to increase the bubble rate, so I have no reason to try to find out how much is in the water. The plants are now doing so well I know there is a significant amount, and thats all I wanted.


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## Hoppy (Dec 24, 2005)

It has been 20 days since I set this system up. My plants are growing much faster, and look much better now. Traditionally it is said that DIY CO2 is a waste of time on a tank this big, 65 gallons, but I'm absolutely convinced that it is a big benefit. Of course you can't run high light and use DIY CO2, but with low light, it makes a world of difference.


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## Hoppy (Dec 24, 2005)

About one month ago, when I started the CO2 going:















Today, after a pruning, water change, etc.

You can easily see how the plants improved with just a simple DIY CO2 system, taking me about 15 minutes of extra work a week replacing the solution in one bottle per week.

Notice that the crypts melted from the sudden change. They should recover very well.


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## driftwoodhunter (Jul 1, 2011)

This is something I may have to try, it would be a perfect "I'm bored, it's winter" project for me! Your clear instructions might just possibly make this a project I can do - lol


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## pandamonium (May 14, 2012)

hey hoppy i was thinking about doing this with my 40 gallon tank. i have low lighting i believe (4 13W CFL bulbs). the before and after pictures look amazing. so if you replace 1 cylinder every week, does the CO2 last for about 2 weeks each?


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## Hoppy (Dec 24, 2005)

The last time I set up a DIY CO2 bottle, on a different tank, one bottle only, it lasted about 3 weeks before the bubble rated dropped much. I'm changing each bottle after 2 weeks just to be sure. By doing the change at night after the lights go off I am back at full 1 bbs before the lights come back on.

The modified "powerhead", actually an internal filter, is a big part of why this is working so well. I still have two more internal filters of different brands, so I assume everyone has at least one laying around.


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## TwoTacoCombo (Apr 13, 2012)

Hoppy said:


> There used to be a very tiny cheap internal filter, the Elite by Hagen, sold only at Petco


Amazon has these for about $8.50. I have one in my beta tank, and they are awesome.


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## thinBear (Dec 16, 2011)

I tried this mod tonight, and break the paddle 


Besides my technique are not as good as you guys (hand shanks a lot after caffeine >_<), i will blame:


the pair of snips are not sharp enough to do the job or
the material of the paddle used by odyssea not quite suit this mod
I can almost feel the plastic deforming as I applying force slow and steadly on the snips, and all the sudden it just go all the way through, and part of the paddle break and fly away like clipping fingernail...

Then I try different method: using a cutter like this:









and it is much easier for me to control; but when I try to blend the paddle, it keep bouncing back to the original position. After few attempts, i can notice the part contacting the center turning color... and finally break apart...

I conclude that the paddle must be made of different material. I am not implying Odyssea using cheap stuff, I'm just saying the material it use does not quite adapt this method.

The power head/ in-tank filter I bought is EX100

Anyway thanks for the guide, I track down the thread you mention on Tom Barr and learn a lot more, hopefully melting so plastic and glues will bring back the device; even if not, it is only a very small lost :icon_mrgr

If I could save it, or do it again for the same equipment, I'd using hot sewing needle to melt, create more surface area, punch holes on the paddle instead.


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## thinBear (Dec 16, 2011)

*this how I fix it*

So, I broke the paddle:
















After reading a bit further on forums, I attempt to fix it:
















and the PH makes lots of noise when I ran it dry without putting into water. Then I remove the attachment except the top layer. Noise has gone when I ran it under water, but the PH has lost lot of power.









this is the leftover from the 1st design and the 3rd design









3rd design: still very weak current pumping out. Then I guess I need to trim out the unnecessary part, also maybe I put the magnet cylinder upside down, thus making the it rotate in reversed direction, which is not optimized by the angled paddles? (Very not sure about this, when I try to rotate the 3D object imaginary to figure out, it hurts my brain...)
















and works finally!
























left is before mod, right is after;
Can't tell the difference to be honest (greatly affect by how much air I feed in) lol


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## Hoppy (Dec 24, 2005)

When you make a paddle wheel like that you are putting a huge power demand on the powerhead "motor", and that slows it way down. Powerheads work by flinging the water radially, not like a fan, blowing it at right angles to the rotor. They generate very little pressure, so the high flow rate doesn't use much power to drive it - power equals pressure times flow rate.

I did a few powerhead rotors with melted holes in the paddles too, but I didn't think they worked as well as the split rotor. If you read Tom's first posts of that method, which as far as I know he devised, he had better results with it than with the holes too. (He was able to put two cuts per paddle, but I couldn't see any way I could succeed at that.)


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## thinBear (Dec 16, 2011)

Thanks for the advise. I will just grab a new one with the exact model mentioned in the thread. The broken blades "unbalance" the rotation and occasionally make some noise which irritates me.


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## herns (May 6, 2008)

Hoppy said:


> I don't get credit for this - Plantbrain originated this modification and tested it out. I'm just finally finding a use for it.
> 
> My check valves finally showed up today.
> 
> ...



I notice a transparent sleeve on the black tubing when it goes thru the bottle cap or it was just from the photo?


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## Hoppy (Dec 24, 2005)

The "sleeve" is just a reflection of the white cap. If I ever do this again, I will definitely get some of those special caps from the online auction site that can't be referenced here.


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## herns (May 6, 2008)

Hoppy said:


> The "sleeve" is just a reflection of the white cap. If I ever do this again, I will definitely get some of those special caps from the online auction site that can't be referenced here.


I've seen them and they are coming from HK. Those cap was made to fit the soda bottle cap. Nice product idea.

Ive had been working a DIY co2 separator using a small soda bottle and was not successful about it. Always leaking. Im getting those special caps on eee b a y.


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## herns (May 6, 2008)

Hoppy said:


> It is installed now! Unfortunately, I didn't have as much sugar as I thought, so I ended up with 2/3 sugar 1/3 Karo syrup. My proportions are 1 1/2 cup sugar/syrup, 1/2 tsp bread machine yeast, 1/2 tsp baking soda, in 2 liters of water, roughly - up to the end of the cylindrical part of the bottle and a half inch higher. I soaked the yeast in slightly warmed water, then poured it into the water/sugar/baking soda mix, and topped off the water.
> 
> 
> 
> ...


I have DIY for my 2g. I hooked up a separator bottle with a special cap I got on eBay & this thing take so long to build pressure. I also change mixture twice thinking the yeast was bad. 

Does anyone had same experience?

Sent from HTC One device using Tapatalk2


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## Hilde (May 19, 2008)

Hoppy said:


> I found these, http://www.wayfair.com/Hagen-Elite-Mist-Air-Stone-A983-4-HGE1777.html at an LFS near me and bought a 3 pack of them, and installed one on the end of the check valve shown below
> 
> Now it makes a lot less noise, just an occasional slight click as a bigger bubble goes through, and the mist in the water is still very good.


I realize this is an old thread but it is exactly what I am trying to do. Do mean the check valve decreased the noise? Mine rattled terrible so next step is to use a bamboo air stone.


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## Hoppy (Dec 24, 2005)

Yes, it is old!! It's bald!!

The noise was the blurp sound when a CO2 bubble hit the little water pump impeller. I used a tiny "air stone" on the end of the check valve to break up the big bubbles into more smaller bubbles. That made the blurp sounds less loud, but more of them. The check valve and air stone were inside the filter compartment of that little water filter.


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