KH/Alk test - off the scale?

[The-Engineer-That-Brews]

Just had a play with the Salifert Ca and KH/Alk tests that arrived yesterday.
Good lord it's been over 40yrs since I last did a titration... brought back a few memories.
CA test was straightforward and gave me 125ppm (versus Ca: 145mg/l from the water company report for 2019).
But on the KH/Alk test I got the full dose of reagent in and it was still stubbornly blue which suggests dKH > 15.7 (Hmmm). Water company 2019 report was HCO3: 333mg/l ... is that consistent, or have I messed up the test?

EDIT: the above result isn't surprising, as the conversion factor suggested here of 17.484 suggests that the water company figure should give a dKH of around 18.6.

Tomorrow I might try diluting my tap water by 50% with the super-pure stuff from my RO+DI setup and see if it measures in at about 9.4.
It will also be interesting to do the KH/Alk test on a sample of the water with Bru'n Water's suggested 'sparge acidification' dose of 0.33ml/l 80% lactic acid.

 

[strange-steve]

You could just fill the reagent syringe up again and keep going until you reach the end point. Off the top of my head I believe the conversion from ml of reagent to alkalinity is linear so you should be able to work it out easily, even though it's off the chart.

 

[The-Engineer-That-Brews]

Ah good point!