Re: pH<7

[Thomas Barr <tcbiii at earthlink_net>]

>> CO2 levels are determined by both pH and KH (refer to the table).
> 
> This is backwards.  The pH is set by the CO2 concentration
> and the KH.  You can find out what the CO2 concentration is by measuring
> the pH and KH.  You can only adjust it by altering the CO2 system or
> the plants or fish or lighting.

It is backwards. I should have said measured, not determined.
 
>> Water with high KH values(HCO3) at equilibrium (like a glass of it sitting
>> on the table for 24 hrs say) has less CO2 and more HCO3 than water with low
>> KH values.
> 
> It will have the _same_ amount of CO2.

Ah, I got that one tangled up:) They do have the same CO2. Slap my face. I
actually deserve it here.

> The equilibrium concentration
> of CO2 in the water is _not_ affected by KH.
 
>> Some folks don't use CO2, some plants and all algae use HCO3 instead of CO2
>> as a carbon source splitting it HCO3=> CO2+ OH. This raises the pH and also
>> softens the water(Removes the KH).
 
>> Soft water(in terms of KH) has more CO2 than hard water does at
>> ****equilibrium****.
 
> No, this is not true.
> The CO2 concentration is dependent on the CO2 system, the fish,
> and the plants, but _not_ the KH.  The CO2 concentration and the KH set
> the pH.

Again thanks Paul, I'm wrong here. I didn't think it through and fired off
the response.  
Regards, 
Tom Barr
> 
> - -- 
> Paul Sears        Ottawa, Canada