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Re: Aquatic Plants Digest V3 #647

Paul writes:

> What about this as an alternative explanation:  CO2 was driven off with
>  chloride salts remaining.

While the HCl was interacting with the CaCO3 this was happening.  But
alkalinity refused to go lower than 40ppm even after several doses.

>  The pH probably rebounded not only from the loss
>  of CO2, but also from more calcium carbonate dissolving from old snail
>  shells, etc. 

No snail shells, no carbonate in the gravel.  Nothing at all to induce this
reaction in a bare tank with nothing but water and a lid.  I can accept the
CO2 loss thing, but pH went down and back up even after the reaction with
carbonates stopped.  And at one time I drove it all the way to 5.0 and the
next day it was back to 7.4.  CO2 can't account for that.

> I never heard that HCl gas was produced from anything but the
>  most concentrated hydrochloric acid solutions.

It does its own equilibrium thing, just like anything else.  I also observed
that the pH would take 30% longer to rise all the way when I used a very tight
fitting lid. on the tank.  Gas-off is the only explanation I have.  Anyone
want to offer another?

Bob Dixon