Testing chlorine when shocking

[KurtV]

John,
Are you using an OTO test? If so, you can dilute the pool water with 2 parts distilled water, multiply your result times 3, and get a rough idea of your chlorine level. Use the same measuring vessel (a shot glass works well) to measure your pool water and the distilled water. Just fill one of whatever you're using with pool water, dump it in a second vessel, repeat twice with your distilled water, mix well, and then fill your comparator tube from that mixture.

If you use an FAS-DPD chlorine test (e.g. the taylor K-2006), you can test up to 50 ppm.