viable to raise CO2 by eliminating surface agitation? - The Planted Tank Forum
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post #1 of 3 (permalink) Old 02-10-2016, 07:06 AM Thread Starter
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viable to raise CO2 by eliminating surface agitation?

I'm curious if eliminating surface agitation would increase CO2 in any significant way? If so, is there any insight into how much? Any adverse effects?

Since there would be no new sources of CO2 (ignoring fish respiration), would CO2 just bottom out at some point and this is really just a stupid question?

Pic of HOB-style filter to show how much surface agitation currently happens.
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post #2 of 3 (permalink) Old 02-10-2016, 09:27 AM
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There are two significant factors that determine the rate of gas exchange. Surface area of the water, and circulation of the water.

It should make sense, that in order for gas to exchange between water and air, requires contact between the water and air. The more contact (surface area) the more gas can exchange at any one time.

Gas diffusion through water is slow. By having good circulation, you ensure that different water is always coming into contact with the air.

When people talk of surface agitation, they really just mean both of these things combined, since agitation of the surface water will increase the surface area of the water, an help to increase circulation.

When you slow the rate of gas exchange to reduce the amount of CO2 lost to the atmosphere, you also slow the rate with which oxygen can diffuse into the water. Life survives well with reduced CO2, it does not survive well with reduced O2. Better to increase the production of CO2 to offset loss to atmosphere, while maintaining good O2 exchange.
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post #3 of 3 (permalink) Old 02-11-2016, 12:51 AM Thread Starter
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Quote:
Originally Posted by Audionut View Post
There are two significant factors that determine the rate of gas exchange. Surface area of the water, and circulation of the water.

It should make sense, that in order for gas to exchange between water and air, requires contact between the water and air. The more contact (surface area) the more gas can exchange at any one time.

Gas diffusion through water is slow. By having good circulation, you ensure that different water is always coming into contact with the air.

When people talk of surface agitation, they really just mean both of these things combined, since agitation of the surface water will increase the surface area of the water, an help to increase circulation.

When you slow the rate of gas exchange to reduce the amount of CO2 lost to the atmosphere, you also slow the rate with which oxygen can diffuse into the water. Life survives well with reduced CO2, it does not survive well with reduced O2. Better to increase the production of CO2 to offset loss to atmosphere, while maintaining good O2 exchange.
Makes sense, thanks!
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