Why Is My Pool Cloudy? Causes and Fixes
Nothing kills pool day faster than walking outside and finding your water looks like skim milk instead of glass. Cloudy water is one of the most common complaints from home pool owners every summer, and the good news is that it almost always comes down to a short list of causes you can fix yourself in a day or two.
Here's how to figure out what's going on in your pool and get back to clear water without guessing.
Start With a Water Test
Before you dump anything into the pool, grab your test strips or a liquid test kit and check your numbers. Cloudy water is a symptom, not a diagnosis, and treating the wrong problem just wastes chemicals and time. You're looking at four things: free chlorine, pH, total alkalinity, and cyanuric acid, also called stabilizer.
The Most Common Causes
Low or Inconsistent Chlorine
This is the number one reason pools turn cloudy in summer. Hot weather, heavy swimmer use, and direct sun all burn through chlorine fast. If your free chlorine has dipped below 1 ppm, or it's swinging up and down all week because you're dosing by memory instead of on a schedule, cloudiness is often the first sign.
A steady supply of chlorine matters more than one big dose. That's the whole idea behind using 3 inch tablets in a floater or feeder instead of shocking the pool every few days and hoping for the best.
Poor Filtration or Circulation
Your filter is what actually pulls the cloudiness out of the water once the chemistry is right. If you're not running your pump long enough, your filter is overdue for a backwash or clean, or you've got dead spots where water barely moves, fine particles just sit there suspended instead of getting trapped. In peak summer, most home pools need the pump running somewhere in the 8 to 12 hour range to keep up.
Water Balance Problems
pH and alkalinity that are out of range make chlorine work less efficiently, even if you've added plenty of it. High pH in particular can cause a hazy, milky look on its own. Get pH into the 7.2 to 7.6 range and total alkalinity between 80 and 120 ppm, and your chlorine will do its job a lot better.
Contaminants and Early Algae
Sunscreen, body oils, sweat, pollen, and windblown dust all add organic material to the water. In small amounts your sanitizer handles it fine. In large amounts, especially after a pool party or a big storm, it can overwhelm your chlorine and cloud things up. A greenish or dull tint mixed with cloudiness usually means algae is starting to take hold, which means it's time to shock the pool in addition to your normal routine.
How to Clear It Up
Once you know what's off, the fix is usually the same short list, just in a different order depending on the cause:
- Rebalance pH and alkalinity first, since nothing else works well until those are in range.
- Bring free chlorine back up to 2 to 4 ppm and hold it there.
- Run the filter around the clock for 24 to 48 hours to physically clear out suspended particles.
- Brush the walls and floor to knock loose anything clinging to the surface so the filter can catch it.
Most cloudy pools clear up within a day or two once chlorine, balance, and filtration are all working together. If it's still hazy after that, retest. Something in the chain is still off.
Keeping It From Coming Back
The easiest way to avoid this whole headache is steady, boring maintenance. That's where we come in. ClaroBlu sells 3 inch Trichlor chlorine tablets at wholesale pricing, direct to homeowners, with no distributor markup in between. Same 99% Trichlor formula with 90% available chlorine that pool stores sell, just without the markup.
As a general starting point, most residential pools do well with about 1 tablet per 10,000 gallons per week in a floater or feeder, adjusted up for hot weather, heavy swimmer use, and lots of direct sun. Always confirm with a water test rather than going on a set it and forget it schedule, since every pool and every week is a little different.
Orders over $45 ship free, and we ship anywhere in the 48 contiguous states, so it's easy to keep a backup case on hand and never run out mid-summer.
The Bottom Line
Cloudy water almost never means something is seriously wrong with your pool. It usually just means one part of the routine, chlorine, balance, or filtration, has slipped a little. Test first, fix in order, and give your filter time to catch up, and you'll be back to swimming in clear water in no time.