CO2 and Surface Agitation - The Planted Tank Forum
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post #1 of 5 (permalink) Old 12-09-2014, 12:37 PM Thread Starter
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CO2 and Surface Agitation

I read somewhere that surface agitation will cause a loss of CO2 in water. I recently started using my HOB filter again, which as anyone could imagine, causes surface agitation. I also use a nice air pump with a couple bubble stones throughout the tank. The bubbles agitate the surface substantially.

So, with all that in mind, what sort of loss of CO2 am I looking at? Would it be a few PPM or like 50% or more? Any speculation or "Yeah, Science!" would be appreciated.
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post #2 of 5 (permalink) Old 12-09-2014, 02:27 PM
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If you like science, watch this guys video's. This one will not directly answer your questions but it's a start.

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post #3 of 5 (permalink) Old 12-09-2014, 02:41 PM
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Hell nex...

The air stones are a nonessential. They don't contribute anything to the workings of the tank. A filter that hangs on the back (HOB) with a gph (gallon per hour) rating of 4 times the volume of the tank in gallons is all that's needed to mix a sufficient amount of oxygen into the tank water.

If you work up to the point you remove and replace half the tank water every week or two to remove dissolved wastes, then this is all the fish and plants need for good health.


"Fear not my child, just change the tank water."
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post #4 of 5 (permalink) Old 12-09-2014, 03:44 PM
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You could find out with a drop checker. Find what you are reading right now. Turn off the air pump and measure again.
If you know how hard your water is (can calculate how much buffering it's capable of), then you could measure the pH fluctuation and calculate it.

FWIW, I had some surface agitation to prevent a bio film and couldn't get my drop checker to read 30ppm unless I turned up so much CO2 that the aquarium looked like a sprite bottle.
I adjusted the outlet for less surface agitation and was able to significantly reduce the amount of CO2 released into the tank to get to my desired levels.
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post #5 of 5 (permalink) Old 12-09-2014, 06:51 PM Thread Starter
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Wow, so much good info here, thanks everyone. That video was interesting too, watched a few more from him while I was at it.

And I use the hardness/pH method to calculate CO2 levels. I think I'll test it out with/without air-pump and HOB filter just to get an idea, don't have any fish in there atm anyway. I use the 2-litre DIY method and it's frustrating to constantly have low CO2, I think agitation is the reason behind it and you guys are confirming that. It does look like a sprite bottle in there just to bring it to 8ppm overnight.
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