For high CH, you may find the below helpful to save on testing reagent. Calsaway is a company in the AZ area providing r/o treatment for pools. A few hundred $'s to lower CH vs risking scale is money saved in the long run...plus you need to lower CYA to make things way easier.
Notes from :
extended-test-kit-directions-t25081.html
Hold the dropper bottles vertically and squeeze gently, so that drops come out slowly and seem to hang on the tip of the dropper bottle for a moment before falling.
If you expect that your CH level is extremely high, you can do the test so that each drop is 25, instead of 10, to speed up the process and save on reagent usage. Use 10 ml of pool water, 10 drops of R-0010, 3 drops of R-0011L, and multiply the number of drops of R-0012 by 25 to get your CH level.
Measuring high CH levels is much easier and more precise if you use a magnetic stirrer.The sample may turn purple during the test, or go to blue for a moment and then turn back to red/pink. This is called a "fading endpoint" and is caused by interference from metal ions. If this happens, do the test again, but this time add five drops of R-0012 before adding any R-0010 or R-0011L. Remember to count the initial five drops in the total.
In extreme cases, a fading endpoint may occur even when adding five drops of R-0012 at the start. If that happens, mix pool water with an equal quantity of distilled water, test that, and then multiply the result by two.
R-0010 is calcium buffer, a strong base which prevents interference from magnesium.
R-0011L is calcium indicator, an organic dye used to provide the red/blue color. It should be a deep blue color. If the dye stains the plastic bottle it is stored in, it has gone bad.
R-0012 is hardness reagent, used to titrate until the color changes.
The precision of the measurement is plus or minus one drop when up to 10 drops of titrant are used, or plus or minus 10% of the final reading, when more than 10 drops of titrant are used.
