Tap Water Test

[waterbear]

Now I just need to learn the difference in pink/red and how blue is blue. Thanks for the advice!

Donnie

The enpoints in the titration tests are very easy to determine. Just add drops until one more drop produces no more color change and then don't count that last drop. For example, with the TA test lets say that 6 drops produces a fleeting red color, 7 turns greyish, 8 turns greyish red, 9 turns red, 10 turns a brighter red, and 11 does not cause any color change at all. Your endpoint is 10 drops or 100 ppm TA.
Chemgeek gave you excellent advise on the calcium test (I do the same thing but I add 6 drops of reagent 1 before adding anything else--been doing calcium tests for many more years than I've owned a pool. It's a standard test for salt water aquairums and I've kept them for about 35 years now!). This will help deactivate any metals that might be present (the titrant in this test is a seqestering agent!) and help get rid of the 'purple floaties' that can make the endpoint of this test hard to see. Once again titirate (add drops) until one more drop produces no more color change and don't count the last drop. Once you get used to it the color change from purple (intermediate color) to light blue is pretty easy to see.
Same thing applies to the FAS-DPD chlorine tests. If you are not sure if the solution has turned colorless add one more drop and if there is no more color change don't count the last drop.