No need to remove the device from the water while swimmers are present. It’s designed to handle waves and activity. However, if things get too rough and you want to take it out while swimming, that’s fine, just remember to put it back in as soon as you’re done.
There is no need to put the sensor cap on as long as the monitor will be back in the pool within 24 hours.
Please ignore any recommendations from pHin while the monitor is out of the water, and for 30 minutes after it’s back in.