Cloudy pool water is one of the most common complaints during the swim season. It shows up without warning, dulls the sparkle of a backyard oasis, and usually leads to a fast Google search that starts with “why is my pool water…”
The truth is, cloudy water is usually not the problem—it’s a symptom. Like a check engine light, it’s the pool’s way of saying something’s off, and ignoring it rarely makes it better. Whether it’s a chemical imbalance, filtration issue, or something drifting in from the backyard trees, the path back to crystal clear water starts with a good diagnosis.
It’s All About What’s Floating Around
Cloudiness happens when particles are suspended in the water. They’re too small to settle to the bottom and too light for the filter to catch, so they just hover there, scattering light and giving the water that milky or hazy appearance.
Sometimes these particles come from nature—pollen, dust, leaves, rainwater. Other times, they come from inside the pool: sunscreen, body oils, hair products, and sweat. Then there’s algae, bacteria, and chemical reactions that leave behind tiny solids. Any one of these can cause cloudy water. Often, it’s a combination.
Chemistry Class, But Poolside
One of the most frequent causes of cloudy water is unbalanced chemistry. Low chlorine levels allow organic material to build up. High pH or alkalinity levels can cause calcium to precipitate out of solution and float around. Add in inconsistent calcium hardness or stabilizer levels, and suddenly the water’s holding more than it should.
Chlorine should be steady and within range. The ideal pH sits between 7.2 and 7.6. Total alkalinity should be between 80 and 120 parts per million. Calcium hardness needs to stay in check, especially in regions like south Louisiana where mineral content in tap water can fluctuate.
When just one of these numbers strays too far off course, clarity starts to suffer.
Filters: The Unsung Heroes
The pool’s filtration system is its liver—it’s there to clean out the junk. If the filter is clogged, full, or running too few hours a day, it’s going to struggle to keep up. Every bit of debris that slips past the skimmer or falls from the air puts more pressure on the system. Eventually, it can’t keep up, and the water starts to cloud.
Sometimes it’s the type of filter. Cartridge filters need regular rinsing and replacement. Sand filters require backwashing. Diatomaceous earth (DE) filters need cleaning and recharging. The type of system determines the maintenance schedule, but all of them depend on regular care.
Cloudy water often clears right up with a good backwash, cartridge cleaning, or longer run time. A tired pump or malfunctioning valve can also throw the system off, so it’s worth checking the equipment if cleaning doesn’t help.
Blame It on the Weather (Sometimes)
Rainstorms can introduce contaminants, especially if they bring in debris from nearby trees or lawns. Windy days can fill the pool with fine dust or pollen. High heat speeds up chlorine loss, and heavy bather loads add to the chemical demand.
When the weather shifts, so does the chemistry. That means testing and adjusting more often—especially during peak summer heat or after a storm rolls through. Covering the pool during storms and running the filter longer after heavy rain can help reduce the impact.
What to Do When the Cloud Rolls In
The first step is testing. If chlorine is low, shocking the pool may be the quickest fix. High pH or alkalinity calls for balancing agents to bring those levels down. If calcium is too high, dilution might be the only option.
Next, the filter needs attention. Clean it, backwash it, or replace the cartridge. Then run it continuously for 24–48 hours while monitoring the water. Sometimes that’s all it takes.
If clarity doesn’t improve, a clarifier or flocculant can be used. Clarifiers help bind tiny particles together so the filter can catch them. Flocculants sink everything to the bottom for manual vacuuming. Both work—but they require careful use based on the system type and pool conditions.
Brushing the pool walls and vacuuming the floor helps loosen up debris and prevent algae from taking hold. If algae is suspected, even if the water isn’t green yet, an algaecide treatment or shock dose will likely be necessary.
Keeping It Clear
Once the water clears, the real goal is keeping it that way. That comes down to consistency.
- Test water weekly—or more often during heavy use.
- Maintain proper chlorine, pH, and alkalinity levels.
- Clean filters on schedule and run the pump for enough hours daily.
- Skim and brush regularly to prevent buildup.
- Manage bather load and encourage quick rinses before swimming.
- Cover the pool when not in use to limit debris.
Cloudy water is rarely a mystery. It just requires a closer look at what’s happening chemically, mechanically, and environmentally. Once the source is identified, the solution becomes much clearer—literally.
