[APD] Re: cooler water holds more gas

[Larry Jones <ljones at usc_edu>]

>> Increased diffusion?  Doesn't the amount of dissolved gas
>> decrease as the temp rises, other things being equal?
>> 
>> Scott H.
> 
> Yes, for all gases. O2, CO2 etc
> Cooler water will hold more gas at equilibrium(eg a glass of water sitting
> on a table after 24 hrs etc) than warmer water.
> 
> Lower cooler temps are good IME for plants. I'd ideally like 72-75F temps
> for 90% of the tanks.
> 
> Regards, 
> Tom Barr

I was going to get to that. I suppose I should have been more clear. But I
am still correct. Higher temperature will increase the diffusion or movement
of gas. But you are talking about saturation. Cold water can hold more
dissolved gas than an equal amount of warmer water. Which is why a cold
glass of water will get bubbles on the inside when left to warm. But I
suppose I mixed my terms which is incorrect. My warm water will be unable to
hold as much gas in this case CO2 but I am not trying to saturated the
water. That would surly kill the fish and possibly the plants too. But I
think the warmer water would cause a more rapid diffusion or movement of CO2
out of the water. Just as the warmer water causes a more rapid movement of
water vapor via evaporation. My point was just that I was loosing and using
more CO2 since it has been hot, a 5lb tank every two weeks. But I may go to
the off at night plan. That should extend my CO2 quite a bit.

Larry Jones 
ljones at usc_edu


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