Cloudy, Hazy, Murky Pool Water
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cloudy, murky, hazy pool waterCloudy pool water? If you can’t seem to clear the haze after several days or weeks, this blog post is for you.

Cloudy pool water has a high level of “turbidity”, to use a technical term. Suspended particles may have come out of solution, or it can be residual matter from a recent algae bloom and treatment.

Here’s a step-by-step method to combat cloudy pool water, and restore water clarity.

Cloudy Pool: Step 1, to restore clear pool water is to balance the chemistry

Use a test kit that has fresh reagents or test strips that are less than 1 year old. Start with a pH test, add pH up or down, as needed, to bring the pH into the 7.2-7.4 range. After pH, test and balance your Total Alkalinity. Alkalinity levels should be between 80-120 ppm, or 140-160 ppm for painted pools. High TA levels can cause excess carbonates and bicarbonates to precipitate out of the water. Lower your Alkalinity by adding a pH decreaser in one area of the pool.

High pH and Alkalinity is frequently the source of cloudy pool water, so start with this simple solution. After these two are balanced, check your Calcium Hardness level. This test should yield results in the range of 180-220ppm. Although it can rise higher than this without a problem, high calcium levels in the pool can cause a cloudy pool. If you need to lower the calcium level, there are few chemicals that will soften the water.

Cal-Treat is a chemical product that bonds to minerals such as calcium, creating larger, more easily filterable clumps. You can also use Metal-Free, which doesn’t really remove the calcium, but binds it up, back into solution. I have heard of others who connect a submersible pump to a water softening tank, and mechanically lower the hardness level. Finally, you can drain and refill with softer water. I have heard of some people using TSP (Tri-Sodium Phosphate) to lower calcium. Bad idea, this will add Phosphates and you may trade a cloudy pool for a green pool!

The last steps in balancing the water to fix cloudy pool water is to check that your chlorine level is stable and consistently above 1.0ppm. Low chlorine levels or inconsistent peaks and valleys, can cause hazy pool water. Also, check that you have a residual of stabilizer, aka conditioner – to help protect the chlorine from the sun. Your level of stabilizer should be between 40-80 ppm.

to fix cloudy pool water, look to the filter!

It’s highly probable that your filtration is largely responsible for your cloudy water. If your pool water balance is and has been very good, and you are diligent in keeping a proper chlorine level, skip to Step 2, and check these things on your pool filter.

How long has it been since you changed the filter media? DE grids may last 10 years, but filter sand and filter cartridges may only last 5 years. Over time, they lose their ability to trap small particles, and can be half as effective as they were when new.

Speaking of DE, or Diatomaceous Earth, is your cloudy pool water really just DE powder floating around in the pool? Usually DE will settle out fairly quickly, but if there is a lot of blow-back, it will cloud the pool continuously. You will notice it on the pool floor, however – which should be a clue.

Are you running the filter pump long enough? A large, very effective filter may be able to do the job in 8 hours, but for most filters, a 12 hour run is necessary, and for some undersized filters, you may need 18 hours of run time to maintain water clarity. Until your water clears up, don’t be afraid to run the pump 24/7 – pool pumps are built for “continuous duty”.

Are you bypassing the filter? Multiport valves and Push-Pull valves, the backwash valves for pool filters, can allow water to bypass the pool filter, if the internal gasket or o-rings are out of place, or other internal problems occur. This will usually result in a lower pressure on the filter pressure gauge, but not always. Incorrect plumbing into the filter valve can really muck-up your filtering. If this is a new filter, check that the pipes are connected to the correct ports.

Finally, is your filter undersized? Small filters may be adequate for colder temperatures or low pool usage, but can fail when they are asked to do some real work, like battling an algae bloom. Small filters may be cute, but can cost you a lot of money in chemicals to compensate for their limited filtering ability.

Two chemicals can be immensely helpful in improving poor filtration. Clarifiers work to coagulate small particles into more easily filtered clumps. Just don’t overdose the pool, as it can do just the opposite; acting as a dispersant. Filter Clean is a product to rejuvenate all filter types by removing oils, minerals and other gunk that gets trapped in your pool filter.

circulation can fix cloudy pool water, murky pool water, hazy pool water

How’s your pool pump doing? Is the pressure normal? Does it sound normal? Cloudy pool water can be the result of a clogged impeller or a clogged suction pipe. In both cases, the pressure will be lower than normal and the pump may make a cavitation noise, like it’s gargling rocks.

Are all of the lines open? Someone may have closed the main drain valve or another skimmer while vacuuming, or for some other purpose, restricting the flow into the pump. Make sure all lines are open, for full water flow into the filter.

Does your pool have enough suction and return outlets to prevent dead spots where circulation is sub-optimal? Small aboveground pools can have one skimmer and one return, but larger, deeper pools should have a main drain and at least 2 returns.

Aim the return eyeball fittings in the same direction to create a circular flow of water around the pool, with just a small ripple on the surface, to push floating debris around to the skimmer. If you have no main drain, however, aim the return lower, to sweep across the deeper parts of the pool.

Air in the system can sometimes give the pool a hazy appearance. If you have tiny air bubbles in large amounts making the pool cloudy, check for an air leak on the suction side of your pump (before the impeller). Most common spots for air leaks are the pump lid o-ring or the pipe that threads into the front of the pump.

Finally, is your pool pump over-sized for the pool filter? Not uncommon on aboveground pools. Your pump size should be matched to the filter size. A pool pump that is too large for the filter will push dirt right through, and milky, murky water will result. If unsure, gather the pertinent data from the nameplates on both pump and filter, and give our pool experts a call, we’ll be glad to advise if the pump is too big for your filter. If not, we can help you find the other reasons for this cloudy pool water problem.

One more thing, if you cannot see the bottom of the pool, don’t allow swimming. It can be an unsafe situation when divers cannot see the pool floor, or when lifeguards cannot see the swimmers easily.


Davy Merino
InTheSwim Blog Editor


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