pH/KH/CO2 question

Hello all. I have been lurking (and learning) around the APD for a while
and have just started to try and apply some of my new found knowledge. I
am in the process of retro-fitting my 29G community tank with some plant
friendly hardware - the first of which was a DIY CO2 setup. I also built a
reactor using a small powerhead and a gravel vacuum (doesn't look like
much, but it seems to work OK - lots of bubbles churning around). 

My question is, based on the pH/KH/CO2 table posted by George Booth, I 
was expecting (and sort of hoping for) a drop in pH. But it never happened.
Am I missing something? I am assuming that I have increased the amount of
dissolved CO2 in the water, and I haven't done anything (that I'm aware of) 
to alter the carbonate hardness - so what gives?

Tank info is: pH=7.6, GH=8, KH=5, temp=78, nitrates<10ppm, 25% water changes
every other week, 12 assorted rainbow fish, one 20W Triton, gravel-only
substrate, and one large piece of driftwood. Filtration is an AquaClear
300 power filter - no UGF. Plants are minimal - some Water Sprite and
Java Fern. I am planning to stock the tank with lots of fast growing plants 
once I upgrade my lighting (next project).

Hoping this isn't a dumb question,

Thom Castrovince         - in blustery New Joisey
castrovince at lucent_com