I've tried searching for this answer but my google-fu is failing me.
I want to create a known sample of CYA concentration. That is to say, when I mix it with the reagent then put it in the viewing tube I should get 40ppm.
For a 50ml sample how much plain water (does it have to have chlorine in it?) to stabilizer liquid do I need to add?
Mainly I want to train my eyes so that feel more confident reading my pool's CYA levels.