CO2 DIY Reactor-Improvements?

After reading about the benefits of CO2 fertilization, I set up a 
generator and reactor today. Is there a way to improve contact between 
the gas and water?

For the reactor, I used a clear 1 inch diameter UGF lift tube pushed 
into 3 inches of gravel. I cut a hole as big as a dime in the lift tube 
just above the gravel. A Fuji film can lid <clear type> with two holes 
drilled became the lid for the lift tube. It just fits. One hole is for 
a tube from the generator < 6C water, 1 t yeast, 1 t baking soda, 2 C 

The second hole through the lid is for the water outflow from a Hagen 
Mini Pro 10 gph power head suctioned cup to the glass. Both the gas and 
water supply tubes protrude down only an inch or so through the lid. 
Except for the gas supply tube and electric cord, this rig started out 
entirely under water back in the corner with my heater in this 29 gallon 
tank. The lift tube was filled with water when I started.

The gas pressure, after five hours, has pushed the water level in the 
lift tube down so that it is only two inches above the water outflow 
hole. The whole thing is so buoyant, now, that it has floated almost all 
the way out of the gravel. The water, falling about 10 inches through 
the gas from its hose, is making bubbles as it hits the surface, but 
this churning area is nearer the outflow hole than I had anticipated.

My pH as measured by the Tetra kit before starting CO2 is between 7.5 
and 8.0 judged by the color. The water shows <also by Tetra> a KH of 8.

I was thinking that I would be able to count bubbles coming into the 
reactor, but my gas outflow is about 10 inches above the water level. I 
had planned to put marbles in the reactor tube <not sure why!>, but this 
won't add anything, will it? Should I weight the whole thing down? Or 
just wait until the reactor settles down? Is there a way to improve 
contact between the CO2 and water?

Maybe I'm OK, and the thing is really working. As I'm about to post 
this, about 8 hours after starting the generator, my pH is down. The 
crazy Tetra pH kit is sure hard to read, but I kept the pre-generator 
sample and the post-gen sample is definitely  a lighter blue. I'm closer 
to 7.5 or even 7.0. 

What is a better brand for a cheap pH test kit? My fish store only 
carries Tetra. 

Is the gas in my reactor all CO2?


Jim Curto
Western Springs, Illinois
jkcurto at tensornet_com