# DIY Co2 Meter



## IUnknown (Feb 24, 2004)

There were some really interesting conversations on the APD today.

[APD] Using a reference KH with a pH probe meter

The idea is to use the same type of design as an ADA Co2 drop checker. The ADA Co2 drop checker eliminates the KH in the KH/PH relationship by using a set KH (using R/O). All you would have to do is have the pH probe in the KH solution, and have an air gap for Co2 to exchange between the solution and the tank water (see figure). Since you no longer have to measure the KH, then a normal pH meter, with an algorithm that mimics chuck gads chart, could give a Co2 reading.

CO2 = 3 x [degrees KH] x 10^(7-pH).

Maybe my next project, try some of the things out from this thread, but give a reading in Co2 ppm. Could probably put these things in line and get a reading that doesn't get skewed by ph buffer, tannins, etc.

DIY CO2 Controller - The Real Thing - The Planted Tank Forum


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