Test the pool water to confirm the free chlorine level
Add liquid chlorine or bleach according to the pool volume and current reading
Use chlorine tablets or granules if appropriate for your pool system
Run the pool pump and filter to circulate the chlorine
Shock the pool if the chlorine level is very low or the water is cloudy
Clean the pool filter to improve circulation and sanitizer effectiveness
Remove debris, algae, and contaminants from the pool
Check and adjust pH to the proper range
Reduce heavy bather load until chlorine levels recover
Re-test the water after treatment and adjust as needed