Q: We went on vacation for a few weeks and came home with a cloudy pool. We serviced it in the spring, and have used it many times already, so why is my pool cloudy?
A: Pool maintenance in early summer is a good idea to get the pool back in top shape for family fun. Despite spring maintenance, pools can still become cloudy quickly. Fortunately, there are several easily identifiable reasons and solutions for homeowners who ask, “Why is my pool cloudy?” » Broken or clogged filters, growing algae, pH issues and chemical imbalances can cause a pool to be cloudy, and this can happen whether the pool has been heavily used or not.
Need a pool cleaning?
A pro can help you. Get free, no-obligation estimates from pool maintenance experts near you.
There may be low levels of free chlorine.
If your cloudy pool has a strong chlorine smell, there may be less free chlorine than there should be and the water may not be sanitized. Chlorine pool treatments have more than one type of chlorine working in tandem to kill microorganisms. If they are out of balance, the water will not be sanitized or clear.
You can use a chlorine test strip to identify if the free chlorine is too low (3 ppm is ideal). If so, the pool will need a shock treatment. For homeowners using a salt chlorine generator, the same is true. Turn off the generator while applying a manual shock treatment to rebalance the pool before it begins to grow algae.
There may be a problem with the water filter.
Pool filters help prevent debris and particles from lingering in a pool. Filters should run at least 8 hours a day to maintain water circulation to collect dirt and debris. If the pool is equipped with bottom drains, turn them on to remove any sediment while the filter is running. Sometimes these filters or valves can become clogged or worn out. Try removing the filter and cleaning it, then backwashing it until clear. Replace filters at least twice a year to keep pools clean and fresh.
Traces of algae can make the pool water cloudy.
Algae is an undesirable sight for any pool owner. Algae occur naturally and are found in plant debris and soil. If you catch algae early in its growth, it is possible to eliminate it before it becomes a significant problem. Green algae photosynthesize quickly, especially on sunny days.
Sometimes chlorine treatments can’t keep up, and an algaecide or pool clarifier can target growing algae, though too much can cause foaming or copper deposits in the water. Be aware that an algaecide is only effective before a major algae bloom occurs and may not work on black algae. In these cases, call a local pool service professional.
Professional pool cleaners in your area are at your fingertips
Clean your pool the right way the first time.
Very high levels of calcium hardness can cause pool water to become cloudy.
Many outdoor pools have hard water, which contains minerals like calcium and magnesium that leave residue. If a pool has a cloudy appearance that won’t dissipate, high calcium levels may be the problem. Excess calcium will visibly gouge the walls of the pool and likely clog the filter with hard mineral deposits. A clogged filter will not do its job. In this case, the pool will need to be partially drained and refilled to maintain the optimum calcium level between 200 and 400 ppm.
The pH of the water may be too low or too high.
Part of regular pool maintenance should include testing the water with pH test strips. Ideally, a swimming pool should have a pH balance of 7.6. Below 7 indicates an acidic pool, but above 7.8 is too alkaline. A pool measuring at either extreme will likely be cloudy. A high pH often indicates excess calcium deposits, and a low pH often indicates more chloramine and less free chlorine. Treat the pool accordingly, depending on the pH.
Chemical imbalances can cause pool water to become cloudy.
In some cases, trying to identify which chemical is out of balance can be a challenge best left to a pool maintenance company. Chlorine isn’t the only chemical to worry about; there is also bromine, phosphate and cyanuric acid. Pool test kits can help check for a chemical imbalance.
Heavy rain can make the pool water cloudy.
Outdoor pools are at the mercy of the elements of nature. Excessive sunlight affects pool water quality just as heavy rain can. If a pool receives a significant amount of rain, it could cause the water to become cloudy as it dilutes the water and causes free chlorine levels to drop. In some cases, excessive rain can even push sediment into the pool and overwhelm the filters with debris. Some debris contains phosphorus which promotes algae.
The flora and fauna of the environment may be the culprits.
Insects, birds and mammals (pets and wild friends) sometimes dive into a pool to cool off. They leave behind dirt, waste and contaminants that can upset the pH balance or clog the filter. Trees drop leaves and pollen which can also cloud the water. A skimmer helps collect debris from the surface, but check chlorine levels frequently in areas where animals, insects, pollen, and debris often congregate in the pool.
Maintaining a swimming pool is not always an easy task, but it is worth enjoying a dip in crystal clear water. If maintenance gets overwhelming or pool problems bother you, a professional can help you keep the pool looking its best all summer long.
Find trusted local professionals for any home project