The pH level in your pool is the chemical that most affects your swimmers. pH is a scale measuring the acidity or alkalinity of a solution. It indicates how acidic or basic the water level is. It should be tested daily at first. Once you become an experienced pool owner, you will need less frequent monitoring of pH levels.
What are the ideal pH levels?
Your pH level for swimming pool water should be between 7.2-7.8. The scale runs all the way from 0-14. Zero is a highly acidic level and 14 is a highly alkaline or basic level. If your pH level falls below 7.2 it can make your eyes sting or burn. If it falls below 6.8, there can be damage to metal parts. On the other had, high pH levels can cause calcium scaling, cloudy water, and filtration issues. If your levels are off the chlorine in your pool wont have a good stabilizing ability.
In other words, just try to keep your pH levels within range to avoid many negative side-effects.
How to adjust your pH levels:
Before tampering with pH levels adjust your total alkalinity. Use a pH increaser or pH plus to increase your pH levels; use a pH minus/decreaser or muratic acid to reduce your pH.