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Does surface agitation decrease CO2?

1765 Views 6 Replies 5 Participants Last post by  plantbrain
In a high tech, co2 injected tank high surface agitation will cause CO2 loss. But then the amount of CO2 in the water is artificially inflated to 25-30ppm.

What about a low tech tank with typical levels of 5-10 ppm? Will surface agitation increase or decrease the amount of gas in the water?

I've seen convincing arguments for both sides. What do you guys think?
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I don't think it really matters in a low tech tank (W/O co2). My 50g uses a wet/dry filter and i don't have any problems. (lol, most of the time)
At first I heard that surface agitation will greatly decrease CO2 levels. Then I was told that it doesn't really matter, as long as your setup isn't mistaken for some white-water rafting experiment... So really, I don't know. I think #2 is probably right though.
If you aren't adding CO2 to the water with a DIY or pressurized system, the amount in the water will be less than 5 ppm, and that will come mostly from the atmosphere. In a Diana Walstad tank you might get a higher level, due to CO2 release by breakdown of organics in the substrate, but I doubt it ever getting near 10 ppm.

Water surface agitation has to help keep CO2 in the water as long as the atmosphere is the only source of CO2. But, if you add CO2 some other way, agitation causes a loss of CO2 down to the equilibrium value with atmospheric CO2.
My non CO2 is at 2-3ppm and is consistent.
The filter might add a little little bit, but most is from the air above.

Tom Barr
Well that's good news. Call me childish, but I like the bubbles
With reduced surface turn over, high submersed should experience larger swings, say 5 ppm CO2 at pre dawn, and near zero a few hours after the lights come on.

With more agitation..this swing/difference between pre dawn and midday should be greatly reduced, or if you have less submersed biomass, less light etc.

Tom Barr
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