How To Clear Cloudy Hot Tub Water (And What Causes It)



Due to the high water temperature and small volume of water in a hot tub, keeping the water clean is a top priority to avoid getting sick.

While spas are visually enticing with their sparkling water and bubbling jets, cloudy hot tub water occurs from time to time and it’s something you should learn how to fix.

Clearing up the tub isn’t difficult, but understanding why this happens in the first place is beneficial so you can avoid this situation in the future.

Is It Safe To Soak In Cloudy Water?

Cloudy water is an indication that there’s something wrong with the water. 

Whether it’s the amount of chemicals or the amount of pollutants, cloudy hot tubs should not be used until the water’s restored to a pristine state.

It may be a minor issue that can be cleared up quickly, but until you inspect things and get to the root cause you won’t know what the issue actually is.

For this reason you should never enter a hot tub that has cloudy water, as it can be a major issue that could affect your health.

What Causes Cloudy Hot Tub Water?

There’s many reasons why a spa can have a problem with cloudy water, with these being the main ones:

High pH And Alkalinity

pH and total alkalinity (TA) are the main levels that need to stay in check when it comes to proper water chemistry.

These two are also inextricably linked like Bonnie & Clyde, Mac and Cheese, or Cheech and Chong. If one of these levels gets pushed from its neutral state, so will the other.

A neutral pH level is between 7.4 and 7.6. Any lower and the water becomes acidic, any higher and the water becomes alkaline (or basic). For TA, the ideal level is between 80 and 120 parts per million (ppm). 

If the TA gets too high, it will cause carbonates to fall out of solution, which will cloud the water. A high TA level will also raise the pH level, and you’ll have to lower both to a neutral state in order to restore water clarity.

Not Enough Sanitizer

Any body of water, be it a pool or spa, needs to have the right amount of sanitizer at all times. 

In spas, this will usually be chlorine or bromine, although plenty of chemical alternatives are becoming more popular these days. Things like biguanide, ozonators, enzymes, ionizers, UV systems and salt systems can all help out with water cleanliness. 

If using chlorine, you’ll need between 1 and 3 ppm in the water, and bromine levels should be between 3 and 5 ppm.

If using an alternative cleaner, the majority of them still require a certain level of chlorine or bromine to be used alongside. If sanitizer levels get too low, contaminant particles will build up and cloud the water.

Too Much Calcium

Calcium is another staple that healthy hot tubs require. If you’ve heard of soft water vs. hard water, this is referring to the amount of minerals in the water.

Soft water feels more gentle because it has less calcium and magnesium, but more sodium. Hard water is the opposite, but it’s also what hot tubs require. The calcium in the tub helps to stabilize both the pH and TA levels, keeping them from fluctuating.

Calcium hardness needs to be between 175 ppm and 250 ppm. If the tub ends up with a level over 300 ppm, the calcium will fall out of solution causing cloudiness.

Too Many Metals

Metals in the water can be another cause of hot tub cloudiness. This can be the result of your water source having high metal content (ie. well water), or it can be from using an ionizer.

When filling up the tub, using a garden hose pre-filter can remove impurities in the water source, ensuring you’re using superior quality water right from the start.

Ionizers work by releasing silver and copper ions into the tub. These are antibacterial agents that are to be used in tandem with chlorine or bromine.

The catch is that these ions can cause cloudy issues in a tub that already has high metal content due to its water source. 

Human Beings

The majority of hot tub pollutants are introduced into the water by bathers. What you put on your body and use in your hair can drastically alter the chemistry of the tub. 

Organic contaminants that end up in hot tubs include body oils, sweat, skin cells, hair, and even urine. 

On top of all that, you may use a host of personal care products that will rub off your person and pollute the water.

Body lotions, sunblock, shampoo residue, hair spray, makeup, and even detergent residue from your bathing suit will cause your sanitizer to work overtime.

When there’s too many contaminants, they’ll eventually use up all the chlorine/bromine, and the tub becomes cloudy as a result of these inadequate levels.

In this less-than-sanitary water, a naturally-occurring fungus known as biofilm has a better chance of blooming in the tub, causing even further problems.

Mother Nature

The importance of using a cover on your hot tub can’t be overstated. This will help keep the spa free of anything that Mother Nature can add to the water.

Rain, leaves, dirt, pollen and various backyard debris can all enter the tub if a cover isn’t used.

While these are all natural debris, they’ll still contaminate the water, causing issues with water chemistry and leading to cloudiness.

Dirty Or Broken Filter

An issue with the hot tub’s filter is a common cause of cloudy water. 

The filter’s job is to remove particles of dead pollutants that chlorine/bromine have killed. Cartridge filters have a finite size. Eventually they’ll catch too many pollutants and become less effective over time. 

The catridge’s media will catch various debris, but it will also catch oil and minerals, which can drastically reduce its ability to filter.

A damaged filter can also occur and cause cloudy tub water. This can be anything from a tear in the media, to a broken end cap. When the filter has any sort of damage, it won’t be fully effective when it comes to keeping the water clean.

Pump Problems

The tub’s pump could be why your water isn’t crystal clear, with various reasons as to why it’s malfunctioning.

For starters, you could have an air lock issue. When this happens, you’ll have zero water flow coming from the pump itself, resulting in uncycled water. This issue is more common after you’ve drained and refilled the tub, but it can happen at any time.

Air could also be leaking somewhere before the pump, which will result in a reduction of the overall water volume circulating through the system. If your tub is leaking water, it will cause the water level to drop below the tub’s skimmer.

Once this happens, the skimmer will suck in air instead of water, and the pump won’t be pushing water through the filtration system.

Another pump issue could be with the impeller. Debris such as leaves and hair can clog it, and it can even break due to a jam in the vanes. An impeller that isn’t moving won’t circulate water, making the tub cloudy as pollutants pile up.

Finally, the amount of time you run the pump could be the problem. Aim to run it at least 2 hours every day, keeping the water cycling so it doesn’t have a chance to become cloudy.

How To Clear Cloudy Hot Tub Water

As you can see, there are plenty of reasons why a hot tub could have cloudy water, but how do you actually fix it?

Balance The Water Chemistry

First, check is the tub’s water chemistry. Chances are high that the cloudiness is caused by chemicals levels that are not in their ideal ranges. 

These levels get out of sorts when there’s a lack of sanitizer in the tub, which allows pollutants to run rampant.

Here’s how to balance the water:

  1. Test the water using test strips, a liquid test kit, or digital testing meter. 
  2. Test for the following levels: pH (between 7.4 and 7.6), total alkalinity (between 80 and 120 ppm), calcium hardness (between 175 and 250 ppm), and chlorine (1 and 3 ppm) or bromine (3 and 5 ppm).
  3. Take a sample of the hot tub water. Plunge a cup into the tub, upside down and elbow deep. This ensures the sample water has been well-circulated.
  4. Flip the cup over and scoop out the water.
  5. Dip the test strips or digital meter into the sample and record the results. If using a liquid test kit, you’ll use it to take your water sample.
  6. Calculate the proper dosage of chemicals needed to restore the water to a neutral state.
  7. Add chemicals to the water and circulate the tub for an hour.
  8. Retest the water and adjust levels if necessary.

Note: Remember to shock your hot tub weekly, and even more frequently if it sees heavy usage. Shocking adds a mass dose of sanitizer to the water to kill off pollutants that the day-to-day sanitizer can no longer handle.

Check The Filtration System

Cloudy water can also be caused by problems with the tub’s equipment and filtration system. The pump should be inspected regularly and the filter should be cleaned every 2 to 3 weeks to keep it operating at peak performance.

Here’s how:

  1. Shut off the power to the tub so you can inspect the equipment.
  2. Remove the side panelling on the tub to expose the pump. Check the pump for any leaks (air or water), and inspect the impeller to make sure it’s not clogged. Turn the power back on and check that the pump is pushing water to the tub. Once finished with the pump, turn the power off again.
  3. Remove the cartridge filter from its housing. Check it for excess debris and look for signs of damage on the media or end caps. 
  4. Hose down the cartridge filter to rinse it of any built up pollutants. If it’s very dirty, soak the cartridge in a deep cleaning solution for 24 hours to restore it. If the filter is torn or broken, replace it.
  5. Place the cartridge filter back in its housing.
  6. Reattach the side panelling to the hot tub.
  7. Turn on the power and run the tub.

Note: If you have a biofilm problem in the tub, no amount of sanitizer and water cycling will fix it. Instead, you’ll need to add a biofilm cleaning product to the water while running the spa in order to break down the biofilm, as well as anywhere it might be growing in the pipes and filtration system.

Consider Draining And Refilling

If you’ve tried the above fixes and the water is still cloudy, it’s best to start from scratch by draining and refilling the tub.

Here’s how:

  1. Add a line flush product to the tub. Let it circulate for 30 minutes so it can make its way into the filtration lines and remove any debris that may be growing in them (ie. algae, biofilm).
  2. Turn the tub off and begin the drain. You can attach a garden hose to either the drainage port at the base of the tub, or to a submersible pump placed in the tub. The submersible pump takes around 15 minutes to drain whereas using the drainage port can take 1 to 2 hours.
  3. Ensure the hose is running the waste water to an area where it’s safe to dispose of. This is usually a storm drain or sewer, but check with your city’s ordinances so you aren’t unknowingly breaking the law.
  4. While the tub’s draining, remove the cartridge filter from its housing and rinse it off. If it’s considerably dirty, deep soak it for 24 hours. If it’s damaged, replace it.
  5. Once the tub’s empty, scrub it down using a spa cleaner and a non-abrasive sponge. Rinse it thoroughly so no leftover suds get into the hot tub.
  6. Replace the drain plug at the base of the tub, and fill it up using water from your garden hose. For superior water, invest in a garden hose pre-filter. This attaches to the hose and filters the water source, so your tub starts with high-quality H2O.
  7. Test the water and add in the necessary chemicals to balance the tub. Turn the power back on and circulate the water for an hour.
  8. Retest the water and make any adjustments if needed. When you’re finished, turn on the jets and enjoy your crystal clear spa.

From Cloudy To Clear!

Cloudy hot tub water doesn’t have one specific cause, so being aware of how this problem occurs can help you best diagnose it.

While it’s an unsightly problem, it’s not one that is impossible to fix. The best case scenario will be to rebalance the water chemistry, and the worst case scenario is draining and starting over.

Either way, transforming your tub from cloudy to clear can be done in only a few simple steps.

Categories: Hot Tub Care, Hot Tub Problems