# powered vs non-powered co2 diffusers?



## andrewwl (Sep 26, 2005)

How much better do co2 diffusers using power, like thru moving water, or whatever else, diffuse co2 compared to non-powered methods, like the ladder, or those co2 "bells"? What's the highest ppm that can be reached without power?

Thanks,
Andrew


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## Dewmazz (Sep 6, 2005)

"Powered" co2 diffusers are able to move more water and enrich the water with co2 faster than "passive" co2 systems. In my 10 gal, I had an originally "passive" co2 airstone attached to the intake of my powerfilter. According to the test results, I had a ppm of >30! I do know that "passive" diffusers such as those handmade of glass provide a more asthetically pleasing effect on the tank, though "powered" diffusers will waste less co2. Hope this helps...


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## MiamiAG (Jan 13, 2004)

Andrew,

I´ve always used passive diffusers. IMO, if the bubble size is small enough, almost all CO2 will be diffused before the bubble reaches the water surface and bursts. The chemists on the board can explain the mechanics better for you than I ever could. However, basically, it's a matter of different concentrations of CO2 in the bubble and outside of it.

Based on this, I´ve always chosen to go passive because it reduces the electrical load of the tank and keeps things simple.


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## andrewwl (Sep 26, 2005)

Most would assume that the powered methods were much more effective, I just didn't know by how much.

30ppm seems to be a standard good level to reach. If that can be achieved without an extra socket being used, then I want to go for it.

So what co2 concentrations have APC members been able to reach with which passive devices?


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## JanS (Apr 14, 2004)

Although many passive devices work very well, the ladder is one I wouldn't recommend. I really don't know if it's any better than just sticking your C02 tube into the water and letting it glug away on it's own.


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## wannabescaper (Oct 14, 2005)

JanS said:


> Although many passive devices work very well, the ladder is one I wouldn't recommend. I really don't know if it's any better than just sticking your C02 tube into the water and letting it glug away on it's own.


This is really the only passive device I've ever used, and I believe it dissolves a good amount of co2. For example:

Fresh CO2 bubble has diameter of 3mm, V=4/3(pi)(r^3)=113.1 mm^3

At the top of the ladder, the diameter is 1mm or so, v=4/3(pi)(1^3) = 4.2 mm^3

I think these are pretty reasonable assumptions regarding bubble size, and this is a 96% effective method!!

Andrew, I think that the highest ppm able to be reached with either passive OR active diffusers is gonna depend pretty heavily on the rate of bubbling!

Unfortunately, I'm still perfecting my DIY method, so I can only reach 20 ppm for a few days with the ladder. (okay, I'm too broke for HP!)

By the way, what filtration are you already using on the tank? It's always good to utilize the sockets you are already using. . .
HTH


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## JanS (Apr 14, 2004)

I hadn't actually taken the time to do those calculations, but here's a pic of what the bubble size is coming out of another type of passive diffuser, which are just a _tiny_ bit smaller than the ladder bubbles.
I just ran down and took a quick pic, so it's not very good, but just an example.


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## andrewwl (Sep 26, 2005)

Hey thanks for all the responses!



wannabescaper said:


> By the way, what filtration are you already using on the tank? It's always good to utilize the sockets you are already using. . .


No filteration, it's a 20L and I swap a 5 gal bucket's worth of water a day. Everyone here seems to use some type of filter though, even on tanks smaller than mine. I like those filters that are away from the tank and have the minimal tubes that hang over the side.


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## brad (Jul 10, 2005)

JanS, I`m assuming the co2 goes through the spiral in the diffuser. What adavantage does that bring?


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## JanS (Apr 14, 2004)

Brad, the spiral is supposed to break up the bubbles along the way, but I really doubt that does much more than the ladder. It has a ceramic disc at the top, and I think that's where they really get broken up.


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## bigstick120 (Mar 8, 2005)

JanS said:


> I hadn't actually taken the time to do those calculations, but here's a pic of what the bubble size is coming out of another type of passive diffuser, which are just a _tiny_ bit smaller than the ladder bubbles.
> I just ran down and took a quick pic, so it's not very good, but just an example.


is that on a pressurized or DIY system?


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## Dewmazz (Sep 6, 2005)

JanS said:


> Brthe spiral is supposed to break up the bubbles along the way


Really? I thought it acted as a bubble counter. The entire bell shouldn't have co2 in it, should it?


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## JanS (Apr 14, 2004)

Bigstick, yes this is a pressurized system.

Dewmazz, I was surprised not to see bubbles in the unit too, but you don't see anything until it's coming out of the top. I have a bubble counter built into my system, so that's not really a concern to me, though. 
I bought it from AquaticMagic, one of the sponsors here, so he may be able to give you better specific details of how it works.
All I know is that it does a great job.


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## czado (May 26, 2005)

Ernie,

Not to nitpick, but you used diameter and not radius in your calcs, though it still gives 96% diffusion following your method. I'm finding your idea of using volume of the bubble very interesting and logical. FWIW, I more doubled the measured CO2 after going to one active diffusor from two passive diffusors (Hagen and DIY bell used together). Perhaps this is due to the estimates in bubble size -- a top of the bubble radius of .7mm is quite the decrease compared to .5mm, for example. Ideas?

Later,
Joe


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## Just_me (Sep 20, 2004)

Jans, to actualy see the bubles in the spiral bubble counter...you have to fill the difuser with water 

otherwise the chamber will be full of CO2 and you wont see a thing


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## wannabescaper (Oct 14, 2005)

czado said:


> FWIW, I more doubled the measured CO2 after going to one active diffusor from two passive diffusors (Hagen and DIY bell used together). Perhaps this is due to the estimates in bubble size -- a top of the bubble radius of .7mm is quite the decrease compared to .5mm, for example.


Joe, you got 2x the co2 even with the same bubble rate, using 1 active diffuser? That's pretty solid evidence. . .not sure what you mean by "a top of the bubble radius of .7mm. . . .



andrewwl said:


> No filteration, it's a 20L and I swap a 5 gal bucket's worth of water a day. Everyone here seems to use some type of filter though, even on tanks smaller than mine. I like those filters that are away from the tank and have the minimal tubes that hang over the side.


I think you mean a canister filter. They provide the easiest source for an active diffuser, if you ask me. Som people build an outside-of-tank diffuser, but I just put  T H I S  one together in like 5 minutes, pretty sure it's 100% efficient! It is just a gravel vac stuck onto the outlet of the filter!


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## czado (May 26, 2005)

Bad explanation - top of the ladder bubble radius of .7mm. I agree disolved CO is the best calculation, but what bothers me is that it doesn't coincide with comparing initial and final volume of the bubble. Only curiosity.


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## JanS (Apr 14, 2004)

Just_me said:


> Jans, to actualy see the bubles in the spiral bubble counter...you have to fill the difuser with water  otherwise the chamber will be full of CO2 and you wont see a thing


Ahh, well that's a very good point. The instructions called for that, and I forgot to do it.... 

Will it hurt anything, or should I take it out and fill it with water? 
Sorry, I don't mean to hijack the post....


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