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Re: High pH

Mortimer writes:

> Sorry, should have been more specific.  I dose with sodium bicarbonate to
>  raise the KH, and did so before I was entirely sure what was going on in 
>  tank due to mistrust of my pH controller.  My bad...

Well, Duhhh !!!!  The KH is a measure of the water's alkaline cabonate ions. 
Alkalinity is the water's resistance to low pH, and will in fact nuetralize 
your H+ ions, which is what acidity is all about.  The higher the KH, the 
higher the MINIMUM pH.  It can be higher than the limit, but if it is low to 
start and you add more bicarbonate, pH will rise to the lower limit 
established by the KH.  CO2 will drive it lower, because CO2 and water mix to 
make carbonic acid, which, if you could get it in a dry form, would be 
hydrogen carbonate.  So if you want the pH lower, don't dump NaHCO3 in the 
water.  :-)