# Simple CO2 diffusor - 99.9% efficiency



## niko

I usually difuse the CO2 by using a powerhead and hooking up the CO2 line in the suction so the bubbles get broken by the powerhead impeller and then fly along the tank. I have such a setup in my 6 ft. tank and tiny bubbles fly from one side to the other with no problem. The efficiency of that method is great - on my 180 gal. tank a 10 lb. CO2 bottle lasted for 3-1/2 months!

The sight of fine bubbles flying all over the tank is not something I completely enjoy. But I know that CO2 is getting everywhere so I tolerate it.

Today I tried something a little different. I know someone else has done it before but the efficiency of the setup really amazed me.

I placed a sponge on the powerhead outflow:









1. Powerhead
2. Sponge
3. CO2 line
4. Suction of water + CO2
5. Coarse pre-filter (so snails don't end up sucked, dying and clogging the suction of the powerhead)

The efficiency of that simple setup is amazing. I can see the bubbles going into the powerhead because the CO2 line that I use is clear. I can also hear the bubbles hitting the powerhead impeller. 1 bubble per second definitely goes goes into the powerhead.

But there are virtually no bubbles coming out of the sponge! You can see very few coming out but they are very tiny - like flour dust - and raise very slowly to the surface. There are no bubbles accumulating in the sponge either. The efficiency of using a powerhead with a sponge is definitely close to 100%. With 1 bubble per second and a powerhead that is about 200 GPH there are almost no bubbles that remain undisolved.

I guess that the tiny bubbles that the powerhead's impeller produces get stuck in the sponge. The 200 GPH flow has time to disolve them and only a few make it outside of the sponge. Then they raise slowly to the surface and have even more time to disolve.

I dislike the sight of equipment in the tank but for a quick and simple solution that combination seems to be great. Especially if used with a DIY yeast CO2 reactor.

--Nikolay


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## schaadrak

Have you had to decrease the bubble rate, or are you still at 1 BPS?


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## niko

1 bps is definitely enough. 3 hours after setting up the diffusor the plants where pearling. 

The next morning the sponge was covered with bubbles that stay inside the pores. A lot of dust-like bubbles leave the sponge but nowhere near the CO2 loss of a regular diffusor (atomizer).

The diffusor has been working perfectly since set up. No fertilizers added to the tank as of today but the plants are pearling very heavy under 2 wpg of light. The pearling is indeed very heavy - strings of Oxygen bubbles from the valisnerias are all over and big (1/4") bubbles from the wide leafed L. ovalis float up every 2-3 min.

--Nikolay


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## Fortuna Wolf

Bump. I'm going to try this out, and report back in a few days or so.


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## K20A2

This is very cool, Ive actually been planning on trying something like this. 

Is there any specific brand of powerhead that would work better then the others for this? And, how many gph should it be rated at for a 30" long 29G tank?


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## furballi

I've been using a Hagen Aquaclear 300 for mechanical and biological filtration, plus CO2 injection. A 5 lb tank is good for 1.7 year (1 bubble per 3 sec...50 gal aquarium).

1. Drill a small 1/16" to 1/8" diameter hole 2" below the water level at the 300's water intake tube. The intake tube is a U-shaped 1" ID tube, with the pump's impeller at one end, and the intake filter screen at the other end.

2. Attach the CO2 line to this hole. The intake tube is translucent, so one can count the bubble.


How this works...
The bubbles rise to the top of the intake tube, forming a small CO2 air pocket. The CO2 gas is dissolved into the incoming water. At very high CO2 flow rate, some of the CO2 gas may be drawn into the pump's impeller. There are two 5.5" x 3.5" x 2" sponge filters downstream from the pump's impeller to catch any remaining CO2 bubble.

The result...very rich CO2 water coming out of the filter without any CO2 bubble. One can vary the concentration of CO2 by adjusting the CO2 bubble rate and the water flow rate.

The 300 is dead silent if you raise the tank's water level to the same level as the 300's return spout. The Aquaclear 70/Aquaclear 300 are the same.


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## essabee

That's interesting Niko!

I was planning something like it, difference passing the DIY CO2 through pores before the suction. Even built couple of the diffusors, changed my plans to incorporate them, I think I will retain them in the set-up even if I don't use them (Posted as: New Idea for CO2 Diffusor--DIY forum).

Wrap the spray bar with a roll of sponge and then I have your setup, and mine and now I can handle more than a bubble a second if I want (I am trying out a DIY CO2 setup for a 250G planted posted as: MY CO2 EXPERIMENT IN U.G.F., SOIL, PLANTED, NATURAL TANK-- El Natural forum)


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## Lucky88

This is very good idea Niko....I was using internal reactor for my 1.5ft tank now but it is too big and affected the view. I also try before using nutrafin diffusor plate but is not effective at all.


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## Ahmad Magdy

Hi Niko, can you send a picture of this setup please


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