Let’s start with recapping why cloudy water is a problem. Sure, the murky appearance is quite ugly for pictures. However, cloudy pool water is also unsafe. The lack of clarity makes it difficult to see swimmers. If you have cloudy pool water, you should not allow anyone to swim.

Common Questions About Cloudy Water

What is cloudy water after all? The “cloudy” look frequently described by pool owners is actually called turbidity.

What causes cloudy water? Turbidity in the water is caused by undissolved particles in the water.

How do you diagnose cloudy water? There are basically two factors that can lead to cloudy water – water chemistry and filtration. The problem can be caused by either attribute, or both at the same time.

How do I start fixing my cloudy pool water? The first place to consider is water chemistry, then move on to filtration.

Diagnosing Cloudy Pool Water: Water Chemistry

When reviewing the water chemistry on a pool, there are a few possible to consider. Each of these factors may be causing the cloudy water.

Low Chlorine – a low chlorine level will cause materials in the water to be un-oxidized. It will also allow algae to grow in the water, leaving a green tint.

High Total Alkalinity – a high total alkalinity level will cause cloudiness because of carbonate materials in suspension that are not able to be dissolved into solution. As the Total Alkalinity approaches 130, the water becomes very saturated and much more prone to cloudiness after routine additions of chlorine shock or soda ash.

High pH – a high pH level will cause cloudiness because of carbonate materials in suspension that are not able to be dissolved into solution. The pH should be around 7.4-7.6. If it is allowed to creep up and over 8.0, the water becomes more prone to cloudiness.

High Calcium Hardness – a high calcium hardness can be a contributing factor, but is generally not the root cause of water cloudiness.

Diagnosing Cloudy Pool Water: Filtration (and Circulation)

If you have covered everything in the water chemistry section and the pool is still cloudy, then it is important to look at equipment issues. This next step will let you be certain that the water is circulating and filtering properly.

In order for the pool water to circulate and filter properly, you need the following key elements.

Adequate Water Flow

The water in the pool needs to “turn over” at least once every eight hours (12 hours for home pools). This means that your pump needs to be able to move all of the pool water through your filter within that time period. If you have a 24,000 gallon pool and want to achieve an 8 hour turnover, then your pump needs to move the water at a rate of 3000 gallons per hour or 50 gallons per minute (GPM).

There are several problems that can keep this from happening. First assess, is the pump performing properly? Then check, are the intakes clogged? See the checklist below for a question guide to troubleshooting adequate water flow.

Adequate Filtration

After water flow has been addressed and water is passing through the filter, the filter media needs to be capable of actually filtering out the particles that are in the water. If those particles are not filtered, you will have cloudy pool water. There are several factors that can lead to poor filtration and eventual cloudy symptoms.

Is the water actually traveling through the filter media?

Check to see if the backwash valve is allowing the water to bypass the filter (bad o-rings, etc). Is the filter allowing the water to bypass the filter media? With a sand filter, there might not be enough sand in the filter, or the sand might be channeled. On a DE filter, there might be a tear in one of the grids or a break in the manifold, or the grids might not be seated properly. On a cartridge filter, the cartridge might have a hole in it.

Is the filter short-cycling?

If the filter needs back-washing a lot more often than normal, then the filter media may be packed with dirt and debris and may prevent it from back-washing as well as it should. A sand filter will often become caked internally with mud and oils that clog the sand and greatly reduce the effective filter area. A DE filter may become caked internally with old DE and dirt and may need a filter cleaning (which should be done 1-2 times a year minimum).

Is the particulate too small for the filter?

Not all filters are created equal. In fact, it is important to understand the difference between each type of filter. The three most common filters are sand, cartridge, and DE.

Does the filter fit the application?

A DE filter that is used on a heavily-used pool will probably have a short life-cycle because of the amount of dirt it is being asked to filter out. If you have a pool that meet this description, the filter should be replaced with a sand filter.

When All Else Fails…

Luckily, if you have exhausted yourself checking everything in this blog, we are still here to help. Guarino’s Pool Service has specialized technicians with decades of pool servicing experience that are eager to help you get back to swimming in clear water. Please fill out our contact form or give us a call at 781 – 480 – 7055.

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