Each drop is HALF a dKH?
Did they change??? My instructions say one drop = 1dKH. Is my alk half what I think it is??? OMG this could explain a lot
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On the calcium one, there is a reagent C and a reagent D. The reagent C is one drop per 50ppm, reagent D is 10ppm. So the first time you count the drops of C to get your rough measurement. Test it again, this time do stop at one drop sooner, and switch to D and start counting drops until the colour change.
So if it's say 390, you'll add 8 drops before you see the colour change (which would tell you 400). So you test again, this time add 7 drops (ie, one fewer than where you got the colour change the last time), then switch to D, and you'd add 4 drops of D to get to 390 at the colour change.