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jfinch 
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 Topic: Nitrogen bubbles
Posted: January 10 2004 at 12:58pm |
Someone asked an interesting question last night regarding how much denitrification is occuring in a tank vs. how much nutrient (nitrogen) uptake is occuring from algae and/or coral. Denitrification results in NO3 converting to N2 gas, which should bubble away into the atmosphere.
A lot of assumptions:
- Generation of 1 ppm of nitrate (NO3) per day.
- All nitrogen generated, exits tank via bubbles.
- Denitrification follows this reaction:
Organic + 124 NO3 + 124 H+ ---> 122 CO2 + 70 N2 + 208 H2O
- Nitrogen follows ideal gas law
- Bubble size = 1 mm diameter
Using those assumptions you get:
8.5 bubbles per gallon per hr
So for a 100 gallon tank, you could expect to see about 14 bubbles per minute from your sandbed if that is where all the denitrification is occuring.
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Mark Peterson
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Posted: January 10 2004 at 8:11pm |
Thanks Jon. That is interesting. Since you called it "assumptions" you evidently don't think that all the N2 gas is forming as bubbles that rise up from the sand. What are your thoughts about where it is all coming from and going?
I'm sure thankful for the edit button
Edited by Mark Peterson
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Jake Pehrson
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Posted: January 11 2004 at 2:24am |
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Thanks Jon.
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jfinch
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Posted: January 11 2004 at 12:00pm |
Mark, you could be right, actually you probably are right (hey, there's always a first time for everything  ). I think the question and calculations were just to show relatively speaking how much N2 is produced. Whether it was a boiling froth of N2 or a bubble here and a bubble there. I thought it was an interesting question that I hadn't really thought about before (or I would have already done the calculation).
edit: oops you've edited your post. Now I'm agreeing with a question rather then your proposition. I agree that much of the N2 produced might just dissolve in the water and enter back into the air when it reaches the surface/overflow/sump/ or somewhere like that.
Edited by jfinch
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Mark Peterson
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Posted: January 11 2004 at 3:48pm |
Sorry for editing after you read it. I just thought that it was sounding too argumentative yesterday so this morning I edited it.
Since it was Jake that asked the question, I'd like to know some of his thoughts about this.
Edited by Mark Peterson
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Jake Pehrson
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Posted: January 12 2004 at 8:05am |
My thoughts are...
interesting.
Not much more to say other then it is good to know, but I'm not sure how to apply this information.
Thanks for the work Jon.
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jfinch
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Posted: January 12 2004 at 8:23am |
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My thoughts were... counting bubbles from the sandbed to determine denitrification would be inconculsive at best. Still, it's an interesting topic (where and how nitrogen is exported) and I wish we knew even more.
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Jake Pehrson
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Posted: January 12 2004 at 11:47am |
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My thoughts exactly, Jon.
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Mark Peterson
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Posted: January 16 2004 at 8:57pm |
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I wonder how many pounds of bacteria are living in our tanks?
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