Bests & Worsts Reviews from Amazon

I already have the regular DPD + pH kit, but I needed a way to test free chlorine accurately above 5ppm, which means FAS-DPD. I also find having the Cyanuric Acid test very useful because when too low your chlorine burns off, and when too high you need to adjust how much chlorine you add (7% of CYA). The test kit also tests alkalinity, calcium hardness, and pH; the latter also including a cool "acid/base test" to determine out how much acid or base are needed to adjust your level. It comes in a very well organized, sturdy plastic case, and the color coded testing cheat sheet on the lid is perfect. It isn't cheap, but it helped me balance the water and clean up some algae, so it was worth it to me. Important tips to save time and reagents: 1 - You don't need more than one scoop of R-0870 if it turns pink the first time. If it doesn't turn pink on the first scoop, try one more. If it isn't pink after two scoops you have no chlorine and shouldn't keep scooping. 2 - For chlorine, calcium, and alkalinity, always use the more concentrated instructions, even if your level is "unknown". 0.5ppm is plenty accurate and will use less than half the product (e.g. for 10ppm chlorine you use 20 drops instead of 50 drops) 3 - Cyanuric acid is only accurate to 100ppm. If you suspect your level is high, you can run a diluted sample as follows: a. Fill the bottle to the 7mL line with pool water. b. Fill the bottle to the 14mL line with tap water. c. Cap and shake to mix for 30 seconds d. Empty half this sample down to the 7mL line e. Finish the test as described (add reagent to 14mL, mix 30 seconds, read) f. Double the resulting value.