Robin wrote:
I think I solved the mystery.

The gravel + water on its own yielded no rise in kh, and neither did
the CO2 into a bottle. But, when I was running the CO2 into the tank
I
used a check valve. (I didn't use the valve when I ran the CO2 into
the bottle.)

Well, the check valve had some type of filtering material. It was
the
only valve in the fish store and I didn't think much about it when I
bought it. I found another valve w/ no filter material and tried
injecting the CO2 into the tank again, and, no extra kh.

I feel silly because I hadn't noticed this before posting!

Hey, I'm glad you found the culprit. Now, on to the real business of
fish and plants!

Contact me off-line if you want a copy of my ph/kh/co2 chart. It
prints nicely and is good to keep taped up near your tank.

montagnard_army at free-email-provider-beginning-with-y dot see-oh-em.

--
Trapper