driftwood & pH

Could a piece of driftwood in my 135 gallon tank be buffer my pH at 
7.6?  After replacing my gravel 6 months ago after finding out it was 
causing my pH and hardness to rise, I haven't been able to get my pH 
down even after bubbling CO2 into the return line from my filter.

I purchased an RO unit which is probably one of the best investments 
you could do if you live in a state that has as hard of water as mine 
does (Utah).  I got the hardness down from over 30 ppm to about 6-7 
ppm by diluting the tap with RO water.  The pH of the tap is 7.6 
and when mixed with RO it remains at 7.6.  

My limited understanding of the chemistry involved leads me to two 

1-  not nearly enough co2 is being dissovled in the tank, so increase 
the amount bubbled in the return line  (an idea I don't like because my tank houses 4 
almost full grown discus who at last if I remember breath oxygen and 
not carbon dioxide), or hook up in my tank the ugly co2 diffuser 
that came with my sandpoint co2 tank to try and diffuse more of the 
gas that is being let out. (those of you who have one know 
what a big green ugly monster it is, not to mention you have to hook 
up a powerhead to it)

2- something is buffer my water.  I tested the gravel extensively, it 
would raise RO water to about 6.8 and then stop, the only other 
object in the tank is a big piece of driftwood?  I got the impression 
that a decaying piece of driftwood would actually lower pH.

Any ideas-  shoot away!
oh- for those of you advising me to just learn to like it, a pH of 
7.6 isn't bad-  My Discus won't think highly of you!

Matt Van Buskirk
j.vanBuskirk at m_cc.utah.edu