Want to buy electronics

        I have a 130 gallon tank that I want eventually to set up as a
plant tank.  To start with I would like to buy a CO2/pH meter system
that can be set to a specific pH and then will automatically add CO2 to
maintain the pH. (I read about one of these system in a inspiring book
by Amano titled 'Nature Aquarium World')

        What I want to know following:

        1) does something like this exist? Where can I get one?  (Is
mail order the least expensive way to go?)  And how much does it cost to
get a dependable unit?  (say I wanted top of the line...)

        2) What sort of limitations do these things have... what range
of pH's can be maintained (i.e. could I keep Tanganyikans which like pH
around 8.0 - 8.5)?

        3) Does anyone have such a system operating?  Anyone have it
hooked up to their Mac?

        Thanks in advance.

Buddy Wiese