degassing setup

Riley S

Gambusia
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Jan 19, 2014
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Minneapolis
I'm going to make a degassing column for an upcoming build using 2 cu ft of bio barrel media, and will probably do an induced draft. Is an air to water flow rate of 2:1 enough to achieve proper degassing? This would allow me to use an Alita air pump vs a small "squirrel cage" blower for an air supply, and would make for a simpler install.
 

Zoodiver

As seen on TV
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Aug 22, 2005
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That should be plenty.
Is there a way to elevate the container of bio media above the tank surface? If so, you could just have the water pour in the open top and flow out of the bottom. It would save you the trouble of the air pump all together.
 

Riley S

Gambusia
MFK Member
Jan 19, 2014
102
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Minneapolis
That's good to know, thanks.

It will be above the water height, however the way it is set up, it will be a closed vessel since it will be fairly close to the ceiling. Air out will be vented out of room, hoping to be able to vent outside. See rough sketch of setup. That's why the air:water question as why I'm thinking I need to pump some air in.

degas.jpg

degas.jpg
 

Cu455

Fire Eel
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Mar 8, 2011
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Why don't you put the air holes at the top of the container or the influent tube.
 

Cu455

Fire Eel
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Mar 8, 2011
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Should of explained that better. Have the suction of the water pull the air through as it passes. Like how skimmers are set up.
 

Riley S

Gambusia
MFK Member
Jan 19, 2014
102
12
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Minneapolis
There are a lot of different ways to degas water, that isn't the issue I have. In my particular case it will be inline with my plumbing, as the final step before it returns to the display. Since it will be enclosed, I need to facilitate the gas exchange, either by introducing air in at the bottom or removing it via vacuum though the top. This way water flows down through the media and is broken apart, as air flows up and strips off CO2 and other gases from the water. I probably won't be using a venturi in this case, as I'm not sure it will be as efficient.

Finding the proper air:water ratio is what I was unsure about and prompted the thread. Most of the info I find about degassing takes me to articles & journals on Science Direct, which I would have to pay for to read. The limited other info I find has 2:1, 5:1 and even as high as 20:1. I know a lot of this application specific and I also know there is some math involved in figuring it all out, which I haven't found. With Matt's background, if he seems to think 2:1 is plenty (maybe even 1:1 would work), then I'm probably on the right track.
 

Zoodiver

As seen on TV
MFK Member
Aug 22, 2005
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Yeah, with a 'normal' bioload the 2:1 will be fine. On my big systems, I will even just run open tops on my chamber, and that is enough to keep the CO2 out and pH pretty stable. The other way you mentioned with a small exhaust fan on the top to pull air out would work just as well.
 
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