Do I need to remove the Sutro while shocking my water?

When shocking your water it's best practice to always remove the Sutro monitor (and everything else) from the water for 24 hrs or until sanitizer levels return to normal.

Shock levels of sanitizer could alter the appearance of the Sutro monitor. 

Keep in mind, the Sutro monitor measures up to 5 ppm Cl2. In order to measure high levels of sanitizer, use a test kit containing the FAS-DPD method or test strip that measures higher sanitizer levels.