TFTestkits has revised the methodology used when performing the CH (Calcium Hardness) test.
This new procedure will give accuracy to within 25 ppm, which is just fine for CH and will save noticably on the reagents you will consume.
CALCIUM HARDNESS TEST: CH is mostly relevant to masonry pools. With too little calcium, your water will leach calcium from your pool walls. Too much calcium in any pool (vinyl, fiberglass or masonry) can cause cloudiness issues in your water. CH readings in the 250-400 range are considered ideal.
1. Rinse and fill the plastic cylinder to the 10ml mark.
2. Add 10 drops of R-0010 and mix. then add 3 drops of R-0011L and mix. Red indicates the presence of calcium.
3. Add R-0012 one drop at a time until the color changes to blue. Multiply the number of drops X 25 (i.e. 12 drops x 25 = 300 ppm CH) Record.