Shot glass method doesn't work with DPD?

[polyvue]

Dilution works with any chlorine test. The OTO test has an upper limit so maybe that's why it was stated that way. DPD goes a lot higher. I do take exception with the tap water comment. Many municipalities chlorinate their water and that can mess up the results. Should use distilled water.

Thanks. I also wondered why Taylor suggests tap water, though the dilutions they suggest would only add a portion of the measurable Free Chlorine, skewing the test upward by perhaps .5 to 1 PPM FC. That's not too much if someone is diluting because chlorine exceeds the test's 5 PPM upper limit, but it does introduce error.

FWIW, if you are going to spend the money on a DPD test kit like the K-2005 you might as well spend a bit more and get an FAS-DPD kit such as the K-2006.

No argument from me! I was thinking of the shot glass / dilution method in the context of a pool owner's ad hoc attempt to measure high chlorine without immediate access to the FAS-DPD test, say, when fighting algae and waiting for their kit to be delivered.

I have never come across anyone who said you cannot do dilutions with DPD [...]

Thanks for the clarification. I just wanted to be sure.

Dilution works with any chlorine test.

[Ohm_Boy]

Dilution does work regardless of test. If you think about it, all of our chlorine samples are diluted - the test tells us how much. That's how it works.
Naturally, further diluting the sample increases the scale and reduces the accuracy by the same factor.