Water used in CO2 Drop Checker?

[pepetj]

I have seen some commercially available CO2 drop checkers instructions stating to use certain amount (e.g. 1ml) of water from the tank and adding the reagent (which I suspect is bromothymol blue).

However in my DIY Drop Checkers I use 4dKH solution which I get by adding a pinch of sodium bicarbonate (baking soda not baking powder) to distilled water (I use distilled water for intravenous use) to which I add some drops of bromothymol blue.

Does the difference in water matters as far as the error of measurement? which one of these two options should be used?

Pepetj
Santo Domingo

 

[dbazuin]

Pepetj,

I f you use water from you tank then there is a possibility that there other acid sources in it that lowers the PH other then the CO2.
It then looks like you got more CO2 then you actually have.

Stick with your 4dhk solution.

I use a test witch come with complete test water.