How to calibrate PH sensor and TDS sensor using ESP32

This is part of a function which is called once every second.
Blynk has a limit of 100 events per 24 hour period, so if PH < 4 for more than 100 seconds then you’ll have used-up your quota of events, and associated notifications/emails attached to that event.

The solution is to use a ‘flag’ variable so that you only log one event for each situation where PH < 4

Read this for more info…