Problem: Cloudy water
Cause: Cloudy water is one of the most predominant water quality issues in the pool industry. Pool owners respond more intently to cloudy water than any other water issue because of its effect on the pool’s esthetic appearance.
As it is identified through mere visual observation, any pool owner can recognize cloudy water and know it is an indication that something in the water requires attention. The difficulty, however, is diagnosing the specific problem and devising a solution that adequately clears the water.
The cloudiness or haziness of water is caused by the introduction of suspended particles that are invisible to the naked eye. A similar analogy would be the particles in air that cause smoke. These impurities are introduced to the water from a myriad of sources—essentially any particulate debris that comes from the surrounding environment, including air, dirt, clay, silt, pollen, inorganic/organic matter, and algae. Microbial organisms can contribute to water cloudiness, too.
Even bathers and source water contribute to the impurities that cause cloudy water. Consequently, pools are constantly exposed to such contaminants and require proper maintenance to ensure a clean and esthetically pleasing swimming environment.
Treatment: To treat this problem, it generally involves narrowing down the cause of the cloudy water to either a chemical or physical property. High pH and calcium, chlorine demand, and algae growth are causes of cloudy water that need to be treated by adjusting the water balance. It can be frustrating, however, for the water to be in perfect balance, but still not look right.
Circulation and proper filtration are important to maintaining clear water. The opening process offers a great opportunity to inspect the filtration system and evaluate the media. If the filter media was not cleaned upon closing, then it should be chemically cleaned during the pool opening. If the media is old and has not been replaced for several years, this is also a good time to install new filter media. Operating the pump 24 hours per day during treatment is a good practice.
Using a clarifier will also help to clear the water faster. Clarifiers generally consist of positively charged particles; contaminants in pool water carry a negative charge. These negatively charged contaminants are attracted to the positively charged clarifier and, as a result, this makes the particles bigger and easier to remove via filtration.
Prevention: To avoid cloudy water issues come spring, the pool should be closed properly by ensuring the water is balanced and has a chlorine residual preferably on the high end (approximately 4 ppm). A winter algaecide should also be added.
In milder climates, or those with warmer winters, a mid-season treatment will be necessary. Once the pool is open and clear, always ensure the filtration system is working properly and run the pump at least 12 consecutive hours per day. It should not be broken into two or four hour increments.
This best practice is explained by the Gage-Bidwell law of purification by consecutive dilution, which states the complete removal of dirt from a pool cannot be achieved over the course of one turnover. It requires a series of consecutive turnovers. The reason for this is pool systems operate by principles of continuous dilution. Purified water that enters the pool constantly mixes with the bulk reservoir, continually diluting the suspended particulates in the water. Therefore, a portion of the water at the circulation system intake (i.e. skimmers and drain) has already flowed through and been purified by the filtration system.
What Gage and Bidwell showed in their study was the amount of dirt removed from the system will only be approximately 63 per cent at the end of the first turnover. As the average pool turnover rate is roughly six hours, running the pump for a lesser period will result in an even lower percentage of water that is cleaned by the filter.
As mentioned previously, a pool system that includes routine oxidation and a maintenance algaecide is best practice during the season. A maintenance clarifier can also be added to the system which will help the filtration system work more efficiently and help keep the water clear.
