Why pool water gets cloudy

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Chemical imbalances are why pool water gets cloudy - and mean it needs TLC!

Chemical imbalances are why pool water gets cloudy – and mean it needs TLC!

It is hot enough to fry eggs on the sidewalk, and you cannot wait to jump into your swimming pool and cool off. Except, on second thought and a visual examination, the pool is so murky that heaven only knows what is in it. Cloudy pool water and other signs indicate that your pool needs help!

Cloudy pool water can be caused by numerous factors, including growth of algae, which happens when the sanitizer/oxidizer levels are inadequate. Cloudy water can happen in either fresh water of salt water pools. If your filter is too small this can result in cloudy water as can poor circulation because the filter is unsuitable, or lack of pool use. Leaves from trees and other debris can turn the water cloudy as can suntan lotion, body fluids and make-up, which cannot be filtered. If your pool water is too hot this can also turn the water into a murky mess.

If the water is not exposed to enough sunlight, this can make the water cloudy. If lawn sprays drift into the pool this will muddy the water.

When the pool turns a hideous shade of green this is because there is a lot of algae in the water. The only way to battle this is via chlorine. This requires shocking your pool.


Salt water pools require salt water chlorinators. Salt water chlorinators monitor the pool water and keep your chemicals balanced.

At the beginning of the swim season, or any time that your pool water turns green, you need to super chlorinate or shock your pool, which entails putting in three to five times the amount of chlorine that you would normally use. This process gets rid of contaminates that have collected and survived over the winter months or which accrue after heavy use of the pool. Shock your pool after the sun has gone down because the chlorine will dissipate more quickly this way. Do not get into the pool until the chlorine levels return to normal.

A pool owner needs to put chlorine in his pool; however, you do not want to put in too much or too little. Chlorine disinfects. It kills algae and germs. If there is too much chlorine in your pool this can cause odor problems as well as irritate eyes. When the chemicals in your pool are balanced the water will be clear and not cloudy or green. The color of the water is altered by the pH level, iron content and total alkalinity. You may have to experiment to find what is the right mix for your pool.

Invest in a pool water testing kit. This allows you to maintain a chemically balanced and healthy swimming pool. If the pH or chlorine levels get out of whack this can corrode pool equipment and cause skin irritation and eye discomfort for the swimmers. Keeping your pool water chemically balanced lessens the chance that bacteria and algae will grow.

When your pool water is balanced this means that it has proper levels of total alkalinity, pH and calcium hardiness. This water is neither scaling nor corrosive but ideal to swim in. When the water is balanced it dissolves rather than holds onto minerals. 

The pH level of the water refers to how acidic it is. After testing your water, you can increase or decreasing the pH levels by adding bases (increasers) or acids (decreasers.) The alkalinity of the water means the ability of the water to resist changes in pH. It keeps pH from bouncing from high to low. To raise alkalinity you add a base; to lower it, you use an acid.

If your pool water is discolored, milky or cloudy looking check your filtration system to see if it is working properly. Backwash the filter and add some chlorine.

When the water is a rusty red color, pipes or other parts of the pool that are made of steel or iron have corroded resulting in rust. You probably need to replace the metal parts.