Here is a list and short descriptions of factors that can affect the quality of your pool water. Please note that all of the information below is generic and will not apply exactly the same way to all pools. Be sure to discuss any questions or concerns with your local pool professional.
Bathing Load - the more people that use your pool, the more disinfectant that you will need to control Algae and to properly sanitize your pool.
Sunlight - the warmer the weather, the faster you will lose the residual disinfectant needed in the pool to control bacteria. You can make the residual last longer by maintaining the proper stabilizer level.
Water Temperature - Most pool chemicals will not last as long in your pool as the water gets warmer. The acceleration is even greater when the water temperature gets above 85 degrees.
Wind & Rain - When you experience periods of wind and rain, these conditions will carry dust, bacterial and even algae spores into your pool. These items will overwork your current chemicals reducing their ability to properly sanitize your pool/
pH - When the pH level of your water rises, the ability of your pool water to disinfect bacteria will decrease. You need to maintain the pH level in the 7.2-7.6 range.
Total Alkalinity - When the Alkalinity level is below 80 PPM, this will affect the pH level and could cause staining in a plaster pool or result in possible algae growth. When the alkalinity level is too high, above 130 PPM, this could cause cloudy water and scaling.