Re: CO2 Diffuser question

Greg and Lisa wrote:
> I am curious as to how far in the tank others ,who have the glass bell ,
> have placed it in the tank..Do you place it a few inches off the bottom or
> half way up the side of the tank etc?

For a couple of years I cobbled together a "system" from discarded 
material at the H.S. where I am the science dept. 
asst./Dumbledore/Quasimodo.
I placed a tremendous glass dome into a 55gallon tank and periodically 
would deliver CO2 to it via plastic tubing from a H.S. chemistry lesson
style gas generator(HCl + CaCo3 (marble chips) produces CO2)  Originally 
I had tried a bell jar but when full it was excessively bouyant.  The 
dome that I found must have been destined to be part of an elaborate 
distillation system many years ago before it was damaged because it had 
a hollow outer chamber which I kept filled with water to weigh it down.

To get back to your original question:  It would rest on the bottom of 
the tank and the approximately 20liters/5gallons of gas would be 
replaced by water as it went into solution.
This was an excellent aquatic plant nursery which supplied the aquaria
throughout the building.  It had to be taken down for administrative 
reasons and has been reinstituted at a new location only today.

Anyhow it rests on the bottom--but it is rather large with a large 
bottom surface area.  The CO2 goes into solution rather rapidly.