# Most effective way for CO2 Diffusion in an Aquarium



## SmoothSailor (Mar 15, 2010)

What would be the most effective way to distribute CO2 in my fish tank?

1. Glass Diffuser







2. In-line CO2 diffuser








3. CO2 line connected to rotating powerhead









What are everyone's thoughts??


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## DarkCobra (Jun 22, 2004)

#2 is most efficient as far as dissolved CO2.

However, if you can successfully blow the bubbles from #1 or #3 around the tank so they stick to plant leaves, that is even more efficient. Gaseous CO2 beats dissolved CO2 any day.

Most reviews of rotating powerheads I've seen on vendor websites are negative. Apparently the mechanism is delicate, and they often break and stop rotating in as little as a week or two.


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## JukeFish (Mar 15, 2011)

@DarkCobra What do you think of #3 vs. feeding the CO2 into the intake side of the powerhead? I'm trying that now. Seems to be effective but it's louder than I'd like.


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## timwag2001 (Jul 3, 2009)

all of the experience that i've had with diffusers vs. dissolved co2. dissolved co2 wins. i've even tried dissolved and misted in the same tank and didnt have results as good as dissolving. 

hands down, the tank that i have that runs the best is with a rex griggs style reactor vs ceramic diffusers, a powerhead with a venturi, or ceramic diffusers being blown around with a powerhead. jus my feelings though, please experiment for yourself and post what you find


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## Dave-H (Jul 29, 2010)

DarkCobra said:


> However, if you can successfully blow the bubbles from #1 or #3 around the tank so they stick to plant leaves, that is even more efficient. Gaseous CO2 beats dissolved CO2 any day.


Source?


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## HolyAngel (Oct 18, 2010)

#2 for sure..


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## houseofcards (Mar 21, 2009)

Effective and Efficient are not necessarily synonymous here.


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## timwag2001 (Jul 3, 2009)

here are some good reads for you dave
http://www.plantedtank.net/forums/general-planted-tank-discussion/21340-co2-revelations.html
http://www.plantedtank.net/forums/g...iscussion/21609-co2-revelations-part-2-a.html


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## houseofcards (Mar 21, 2009)

Actually in that first link plantbrain talks about the benefits of using an in-tank diffuser and having pure co2 blow right on the plant leaves as the superior method compared to completely dissolving the co2 into the water column.

Personally I think your splitting hairs. Even if the bubble contact method was superior, in probably 95% of setups the plants are getting what they need regardless of method, unless you possibly have some ridiculious light setup or other condition that might require the one method over the other. Also the dissolution method is probably easier to implement in most setups especially larger ones.


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## drbotts (Apr 10, 2011)

I was asking this question and I did something similar to this. 

Linkhttp://www.youtube.com/watch?v=vwgmu9faaH4

I took a bottle, upside down, and let the bubbles float up into it. I cut a hole in the side of the bottle and sealed it with silicone. The pump then shoots water which circulates inside the bottle and dissolves 99% of the bubbles.

I say 99% because every now and again a micro bubble escapes out the bottom.

Took me 10 minutes to make with spare parts.


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## DarkCobra (Jun 22, 2004)

houseofcards said:


> Personally I think your splitting hairs.


I think that's an excellent point. Though the OP did ask for opinions on the most efficient, any of those methods will get the job done; and in practice, not really be much better than the others.

The best choice often comes down to other factors, like maintenance. Glass diffusers tend to clog every few weeks and require cleaning. The inline diffuser may go months or years without cleaning, but then may be very hard to clean since it can't be disassembled.

And reliability. The ceramic inserts for glass diffusers can break if handled roughly. The fittings and body on that inline diffuser have broken for a few people, causing leaks. And I've already mentioned the rotating part of the powerhead breaking, though even a non-rotating powerhead will still diffuse CO2.


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## Dave-H (Jul 29, 2010)

houseofcards said:


> Actually in that first link plantbrain talks about the benefits of using an in-tank diffuser and having pure co2 blow right on the plant leaves as the superior method compared to completely dissolving the co2 into the water column


That is interested, but not exactly scientific or even well-written. Certainly there is great anecdotal evidence that diffusers have advantages, and some of the proposed reasons make sense. But wow, the writing style is truly off-putting and isn't exactly humble (to say the least). With such a dogmatic, unforgiving, and professorial tone it's hard not to question the conclusions as they are devoid of scientific method and exploding with arrogance and hubris.

That said, I tend to agree with your comment that this is likely splitting hairs. I love my reactor because it's easy, low maintenance, I don't have to look at it, and I don't like bubbles. If the plants could be a bit healthier with another technique, so be it


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## wkndracer (Mar 14, 2009)

Reactor for me because the bubbles everywhere bother me to no end.
I don't believe anything to be more effective either but even if it was the bubbles would drive me nutz!


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## Sharkfood (May 2, 2010)

Powerhead/ lift tube method seems to work very well. Splitting the impeller blades makes for very tiny bubbles which blow around the tank instead of rising to the surface (There's a picture laden guide on the Barr Report somewhere.). I use this method in my grow out tank. It also works well with DIY CO2. Very effective, but makes for a misty morning in your tank which can be annoying to look at.

The Grigg's style reactor is my favorite as it keeps microbubbles out of the tank and hides all the equipment, making it the most aesthetic method IMO.

Glass diffusers are my least favorite method. Much CO2 is lost, and distribution is poor. Blowing a powerhead across the top of the diffuser can address these issues fairly well, but I still feel that the powerhead/lift tube method is better.

Commercial diffusers like bells, and bubble ladders are horrible ways to get CO2 into your tank.


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## Sharkfood (May 2, 2010)

BTW I would suggest routing your CO2 into a lift tube under the power head rather than connecting it in the way shown in picture #3.


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## SuperWen (Mar 24, 2011)

ISTA maxmix CO2 reactor:


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## xmas_one (Feb 5, 2010)

none of the above.


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## takadi (Dec 13, 2010)

Superwen where do you get that particular reactor? There only seems to be one source online.


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## SmoothSailor (Mar 15, 2010)

*Good points*

:bounce: Thank you everyone for your responses. My current set up is a ceramic diffuser under the intake for my marineland canister filter. I have found that my diffuser is getting "clogged" with algae. I have also noticed that the water in my tank is developing a biofilm on the surface. I thought that perhaps a biohead would not only help with the film, but also add CO2 to my water. 
I am thinking more about going with option #2, inline CO2. Cleaning was mentioned as a possible disadvantage....how do you clean them?

Thanks again.


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## esworp (Mar 20, 2011)

I vote for the vortexty reactor. 

i built one. take a look.


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