Is there a way to increase KH without increasing pH?

Add calcium carbonate, and inject CO2. :-)

I have soft water (tap seems to vary between GH/KH=2 and GH/KH=3), but they
add something in the water to make the pH very high (fresh out of tap is
close to 8.0).

Is that the real pH, though? Often, the pH out of the tap is not the real pH
of the water. The water may have extra CO2 in it, or be CO2-depleted. You
should leave it in a bucket overnight, then measure the pH. Or aerate a cup of
water for 20 minutes, then measure the pH. That will give you the real pH of
the your water.


Leigh

http://www.fortunecity.com/lavender/halloween/881/