Sanitizers disinfect pool water and protect bathers. The pool water should be tested daily to make sure it is properly balanced using pH+ or pH-. Stabilized chlorine(if that is your chosen option) needs to be added to make the pool water safe. Also 'shock treatment' (oxidation) on a regular basis throughout the season is critical. Using a good shock treatment helps to avoid the water becoming dull and cloudy and prevents the development of any bacteria which have not been eliminated by the daily treatment..
Stabilised Chlorine is a basic sanitizer which has an ingredient to slow down disipatation by sunlight.