Why is my pool cloudy?

Particles too fine for the filter to catch, or minerals coming out of the water. The common causes:

• Low free chlorine. Germs and the start of an algae bloom cloud the water before it ever turns green.
• High pH or alkalinity. Calcium drops out of the water as a fine white haze when either runs high.
• High calcium hardness. The same haze, and it often shows as scale on the tile too.
• A dirty or worn filter, or a pump that does not run long enough to turn the water over.
• Rain and runoff, which dilute the chlorine and wash dirt and pollen in. See why a pool goes cloudy after rain.
• Dead algae after a shock, which clouds the water until the filter catches it.

Milky white usually means calcium coming out of the water, either because the pH or alkalinity is running high or because a calcium hypochlorite shock went into water that was already hard. Bring the pH down to about 7.2 to 7.4 and keep the filter running, and the haze usually clears as the water comes back into balance. The targets are in pool chemical levels for Florida.

Yes. A filter that is overdue for cleaning lets fine particles pass straight back into the pool, and a pump that runs too few hours never gets all the water through it. If the pressure gauge reads about 8 to 10 psi above its clean reading, clean or backwash it. See how often to clean a pool filter and how long a pool pump should run.

First make sure the test is reading free chlorine and not total chlorine. Then look at pH, alkalinity and calcium. If all of those are in range, the problem is almost always filtration: a filter that needs cleaning, a cartridge that has been cleaned so many times it no longer filters well, or a pump that is not running long enough.

Better not to. The CDC warns that cloudy water can be a sign of more germs in the water than normal, and says to make sure you can see the drain at the bottom of the deep end before you get in. Cloudy water also hides a swimmer who is in trouble.

Usually one to three days once the cause is fixed and the filter runs around the clock. Chemistry problems clear fastest once the pH and chlorine are right. Cloudiness from dead algae after a shock can take a few days of filtering and a filter cleaning or two. If nothing has changed after three days of good chemistry and nonstop filtering, look hard at the filter. A pool that goes from cloudy to green is past that point, and a green pool cleanup is the faster fix.

Yes, and if the cloudiness settles to the floor overnight you should. Vacuum slowly so you do not stir it back up. On a sand or DE filter, vacuum to waste when there is a lot of it, so it leaves the pool instead of clogging the filter. Cartridge filters have no waste setting, so clean the cartridge afterward.

Keep free chlorine and pH steady, run the pump long enough every day, and clean the filter before the pressure climbs. In a Florida summer that means testing at least twice a week. Our weekly pool service covers all three on every visit, with every chemical included in the price.