Home » 10 Reasons Hot Tub Water is Cloudy and How to Clear It

10 Reasons Hot Tub Water is Cloudy and How to Clear It

Hot tubs occasionally become cloudy, hazy, or foamy. If you cannot see the bottom of your hot tub, it’s a sign that something needs to be fixed. Fortunately, common issues usually cause hot tub water to be cloudy and are easy to fix.

Spa or hot tub showing brown ring or cloudy biofilm
Spa or hot tub showing brown ring or cloudy biofilm

Proper, routine maintenance is important for your hot tub’s overall health and aesthetics, and for the swimmers. Proper maintenance will prevent the hot tub from having these issues. Here are the 10 leading causes of cloudy hot tubs and how to fix them.

Steps to Clear Cloudy Hot Tub Water

Here’s a summary of the exact step-by-step process to clear cloudy water in a hot tub:

  1. Clean or replace the filter
  2. Check the pump
  3. Test the water
  4. Balance the chemicals
  5. Add enzymes
  6. Shock the water   
  7. Add Clarifier
  8. Drain and refill the hot tub

Keep reading for a step-by-step guide on how to fix and clear your cloudy spa water.

Defining Cloudy Hot Tub Water

Before we look at the issues that cause cloudiness, let’s define the different clarity terms. Cloudiness is a hot tub that contains small bacteria, germs, or particles that float on the surface. Some people call this foggy or murky water.

Milkiness is when the hot tub has a white tint, making it difficult to see the bottom of the hot tub.

Foamy water builds up on the hot tub’s surface due to body oil, lotions, or cosmetics.

Why Your Hot Tub is Cloudy

Spa hot tub foam biofilm
Spa hot tub foam biofilm

When a hot tub turns cloudy, it’s usually because of a chemical imbalance, not an extreme circumstance. 

Cloudy water can occur regardless of the brand of your hot tub or whether it’s an inflatable model or a standard acrylic or wooden type. Whether it’s a Bullfrog, Intex, Coleman, Hot Spring, Master Spa, Cal Spa, Sundance, Jacuzzi, or any other brand. The good news is that these steps will work regardless.

Below are the top ten reasons a hot tub turns cloudy and the best solution for each problem.

1. Improper Alkalinity Levels

The ideal alkalinity level for a hot tub is between 80-150 ppm. Alkalinity measures substances like carbonates and bicarbonates. If the total alkalinity level is higher than 150 ppm, the carbonates are released from the solution which results in cloudy water in your tub.

High alkalinity can also damage the metal parts of your hot tub. The pumps and jets will corrode if high alkalinity isn’t properly balanced.

If your alkalinity is lower than 80 ppm, it can drive your pH level down, causing the hot tub to be more acidic. Low acidity results in dry and itchy skin and can cause irritated eyes. If your pH levels are low, you should check the alkalinity to see if that’s the culprit.

2. Improper pH Levels

The proper pH level for your hot tub is 7.0-7.4 ppm for bromine and 7.2-7.6 for chlorine. As stated above, with the alkalinity levels, other chemical imbalances will cause the pH to drop. A high pH can cause cloudy water, irritated eyes, and scale formation.


A neutral pH level prevents unhealthy bathing conditions and indicates that the other chemicals are well-balanced. When the pH is higher than 7.6, the water becomes alkaline and reduces the effect of chlorine.  

Low pH means the water is acidic, a health issue that can damage the hot tub’s equipment. It also causes chlorine inefficiency, which may then result in cloudiness due to bacteria and algae growth.

Bromine is less affected by a high pH and can sanitize the hot tub even if the pH is between 7.8-8.2. Bromine is also effective with a pH as low as 4 ppm.  Not only does low alkalinity affect pH, but low pH also affects alkalinity. Alkalinity and pH are closely related, so when one is out, the other will usually follow.

3. Low Sanitizer Levels

Man using chlorine tablet for hot tub
Chlorine tablet for hot tub

Whether bromine or chlorine, the low sanitizer will also cause cloudy spa water. Sanitizer is added to prevent bacteria from growing and should be between 4-6 ppm if you use bromine and 3-5 ppm if you’re using chlorine.

If the chlorine level dips below 1 ppm, foreign particles form, and contaminants grow rampant. These particles form the cloudiness that you see. On the opposite end of the spectrum, high chlorine levels will make the water cloudy because it will oxidize the other minerals in the hot tub.

4. Soap, Lotions, and Cosmetics

group of young people enjoying and relaxing in hot tub

This is probably the most common issue hot tub owners face. Unless people shower before entering your hot tub, these personal products can’t help but rub off into the water. These products introduce phosphates, oils, detergents, and other chemicals into the water.

When these chemicals are introduced to your hot tub or Jacuzzi, they consume the sanitizer and clog the filter, which makes the water cloudy and foamy. If your hot tub has a heavy bathing load, you can expect cloudy and foamy water.

5. Filter Dirty or Old

Filter problems are notorious for creating cloudy and sometimes foamy water. There are multiple reasons why your filter can cause cloudy water. It could simply be dirty or positioned wrong. Or, it’s been too long since it’s been replaced.

Hot tub technician performing scheduled maintenance
Dirty filters can cause cloudy water.

If the filter is dirty, it cannot trap the particles and organisms in the pleats. So, the organisms will be reintroduced into the water when the water recirculates. If the filter is positioned wrong, the water bypasses the filter altogether and reintroduces the organisms back into the water. Which will result in dirty, cloudy water.

Filter cartridges can also become gummed up with minerals or oils, which reduces the filter’s ability to trap small particles. All of these issues cause the filter to not be able to do its job properly and will cause the water to foam up or become cloudy.

6. Not Running the Pump Long Enough or Too Slow

Just like filter issues, a faulty pump can cause cloudy, foamy, or milky water for myriad reasons. One of the more common issues is that the pump isn’t being run long enough. Another common issue is that the pump is running at low speed or too slow, which means the water is not filtering fast enough to rid the contaminants.

The problem could lie with the pump impeller. If it’s clogged with small debris like pebbles, leaves, or hair, it greatly reduces the water flow. The impeller vanes are small and clog easily, which will greatly decrease the water flow.

An airlock will cause no water flow. You’ll know if it’s an airlock if no water is flowing from your pump when you turn it on. This generally happens after you have drained your pool. Last, if the pump isn’t working at all, you will have cloudy water.

7. Calcium Hardness

The calcium level in your hot tub should be between 150-300. Calcium builds up over time if the hot tub is not properly cleaned and maintained.

Over time, the excessive amount of dissolved particles will cause scale buildup in and around the equipment and cause the water to become cloudy. If the pipes become excessively cloudy, the water won’t flow properly and this also causes cloudiness.

Calcium hardness issues are most common in areas with hard water and is introduced through the fill water. 

8. Cloudy Fill Water

As mentioned earlier, a notorious culprit of cloudy water is too much calcium from the fill water. The fill water could also be cloudy or high in minerals and solids, thus causing the hot tub water to be cloudy. 

Cloudy fill water introduces particles and organisms into your hot tub that must be treated immediately (within 24 hours), or it will throw off the chemical balance, which also causes milky or cloudy water.

9. Biofilm

Close up view of a biofilm in the hot tub or spa
Close-up of a biofilm in the hot tub or spa

This is a rare issue, but it’s important to know if you’re troubleshooting water clarity issues. Biofilm is a slimy bacteria caused by algae, fungus, and airborne contaminants that coat the interior of pipes and fittings. If it gets out of hand, it will leave slimy flakes on the surface of the water, which produces cloudiness.

In extreme cases, biofilm causes foaming. Biofilm forms quickly when the spa has sat empty for some time. The bacteria creates an outer layer to protect itself from sanitizers and can become a real nuisance to get rid of. It’s best to prevent it from growing by maintaining good chemistry and sanitation instead of treating it.

10. Biguanide problems

This is another rare issue that occasionally happens if you use a PHMB sanitizer. The level of biguanide in your hot tub should be between 20-50 ppm. Any higher and your pool will be cloudy.

If you have a cloudy pool caused by high levels of biguanide, the filter will be clogged as well, contributing to the cloudiness. Since PHMB is a polymer-based sanitizer, it will leave gummy residue in the filter, preventing proper airflow.

How To Fix Cloudy Water in Hot Tub

 So, now that we know the reasons why hot tubs turn cloudy let’s learn to fix cloudy water in your hot tub.

As I said earlier, cloudy, foamy, milky spas or Jacuzzis are usually a simple problem that can be treated by rebalancing the chemicals. The most drastic option is to drain and refill your hot tub, which should be done every 2-3 months anyway.

If you have any water clarity issues, cleaning or replacing the filter after you fix the problem is a good idea. There’s a great chance that the particles or bacteria lodged in the filter (if not, your water would still be cloudy), and if it’s not cleaned or replaced, it still has a chance of returning to your hot tub.

Step 1: Clean or Replace the Filter

Hot tub technician performing scheduled maintenance
Hot tub technician performing scheduled maintenance

If you have an issue like cloudiness, it should be cleaned before and after the treatment. You clean the filter before the treatment because if it has contaminants, they will reenter the hot tub when the water cycles through it.

The hot tub filter should also be cleaned monthly for routine maintenance. 

Step 2: Check The Pump

Internal component of a spa that shows rust on the pump due to water leakage
Leaking hot tub pump can cause cloudy water.

Whilst you’re cleaning the filter, it’s a good idea to give the pump a once over.

If mechanical issues cause cloudiness, the pump is usually the reason. If the water is not circulating properly, the water will cloud because it cannot cycle out the contaminants. The first thing to look for is if it’s running. If it isn’t, check the breaker and the timer.

Turn the pump on and feel the water flowing out of the return jets. Make sure it doesn’t seem weaker than normal.

Next, make sure the pump is not on low speed. If all the hot tub conditions are ideal, low speed is okay. However, the pump will work harder if the water isn’t circulating properly due to a dirty filter or clogged plumbing.

Finally, you want to check for water leaks. If it leaks, you’ll see water dripping around the pump or lines.

Step 3: Test The Water

More than likely, your water is cloudy due to a chemical imbalance. Your hot tub chemicals should be tested weekly to ensure that the chemicals are within range. If not, the chemicals should be rebalanced. If this is done, the chances are slim that your hot tub will become cloudy.

Alkalinity, pH, and sanitizer levels work hand in hand, and improper levels of each are usually the reason for your water to become cloudy or milky. A solid testing kit like the one from Taylor will provide accurate readings of your chemical levels. You can get the product here:

Taylor K2005 Pool Test Kit
  • Tests for Chlorine, Bromine, pH, Total acidity, Calcium Hardness and Cyanuric Acid
  • Extremely accurate
  • For pools or spas

The proper chemical levels are:

  1. Chlorine or bromine: 1-3 ppm
  2. Alkalinity: 80-150 ppm
  3. pH: (for bromine) 7.0-7.4 ppm (for chlorine) 7.2-7.6 ppm

Step 4: Balance The Chemicals

Balancing your hot tub chemicals is your first defense in preventing cloudiness. Here’s a breakdown of what each chemical does and how it affects your hot tub’s chemical balance.

Increase/Adjust the Alkalinity 

Water alkalinity measures your water’s ability to neutralize acids. Essentially, it is a buffer that helps the water resist drastic changes in pH. If it’s too low, it’ll drive down the pH level too, which has unique problems. The solution is to add an alkalinity increaser to your hot tub and double-checks that the pH is balanced. 

You’re aiming to have the alkalinity at around 80-120 ppm. 

Here’s an alkalinity increaser I recommend:

Clorox Alkalinity Increaser
  • Increases total alkalinity in pools and spas
  • Granulated powder/fast dissolving
  • Sodium carbonate

Adjust the pH level

Since low or high pH levels affect the water clarity in your hot tub, I’ve included it in one step. Like with alkalinity imbalances, if you correct one, you need to check the other. pH and sanitizer levels are the most common reasons why water becomes cloudy and one of the easiest to fix.

You can add Sodium Bisulfate to lower the pH and Soda Ash to increase it.

Clorox pH Down
  • Reduces pH to protect equipment and surfaces
  • Optimizes sanitizer efficiency & helps prevent algae
  • For pools and spas


There are three types of sanitizers for a hot tub: 

  • PHMB (aka polyhexamethylene biguanide)
  • Chlorine and;
  • Bromine 

Of the three types, bromine is a more popular choice because it isn’t as harsh as chlorine. Biguanide (PHMB) is rare and carries unique problems of its own. Chlorine is well known, but many hot tub owners shy away from the strong odor and the harshness on their skin, which is elevated by the heat of the water.

Another advantage of using bromine as a sanitizer is that it is more neutral than chlorine. This means the chemical levels can be higher or lower than chlorine without affecting the chemical balance.

Still, the levels can go out of range, whether it’s chlorine or bromine. If the level is too high, it can be diluted by leaving the cover off and the heat pump on because the heat from the hot tub will make the sanitizer dissipate faster. The other solution is to drain a little water and add some fresh water.

If the sanitizer levels are just a little under range, you can add more chlorine or bromine to bring the levels back up. If the levels are way under range, you can add sanitizer shock. Shocking is just adding a high dose of sanitizer. Usually, bromine or chlorine, but there are non-chlorine/bromine shocks. If you add shock (chlorine or bromine), you should not use the hot tub for 24 hours after you shock it.

Once the treatment is complete, clean the filter again to eliminate any particles trapped during the treatment. If the filter is heavily contaminated, it is best to install a new filter. Installing a new filter ensures no contaminants are present to reenter the hot tub.

Step 5: Add Enzymes

An enzyme-based water treatment product will eliminate and help prevent biofilm formation in the hot tub and plumbing. It will also help to break down other contaminants making the sanitizer more efficient. You can add enzymes on a regular basis to help keep the water clear.


Brown biofilm in the spa or hot tub.
Brown biofilm in the spa or hot tub

Biofilm is a bacterial growth that often produces a slimy coating. Clearing your hot tub of biofilm requires effort, especially if the issue is severe. You should focus on the plumbing before the hot tub because that is the source.

To get rid of biofilm, the first step is to remove your filter and clean it. If the filter is bad, replace it or soak it in heavily chlorinated water for 48 hours. Super chlorinate the hot tub during the same period so that the chlorine will penetrate the plumbing.

After 48 hours, drain and refill the hot tub and treat the water with an enzyme product to eliminate the rest of the biofilm and prevent it from growing again. Spa Marvel Cleanser is a good enzyme product that penetrates plumbing and equipment. You can get it here:

Spa Marvel Water Treatment & Conditioner
  • Gentle to the skin and hair
  • Conditions water for sensitive skin
  • Odourless
We're industry experts and only recommend products we would use ourselves. If you click this link, we may earn a commision at no additional cost to you.

 Step 6: Shock the Water

Shocking the hot tub means adding a high level of bromine or chlorine at one time. Shocking your hot tub will clean and clear the water and kill bacteria. Shocking is the next step if your pool is cloudy and you balanced the chemicals.

You should have your hot tub running while shocking because this helps mix the shock into the water. The high concentration of shock will also clean the plumbing. Shocking should be done once a week for preventative maintenance.

Step 7: Add Clarifier

An ounce or two of clarifiers per week will help your hot tub to stay clear if the chemicals are balanced. Clarifiers attract dirt and particles together so the filter can cycle them out. If you add a clarifier after you check and balance the chemicals weekly, your hot tub should remain clear.

If your hot tub is cloudy due to cloudy fill water, add the proper amount of sanitizer and add 3-4 ounces of clarifier as soon as your hot tub is filled. The water should clear up within 24 hours. If it does, clean the filter and test the chemicals again. If the cloudiness persists, drain and refill the hot tub.

You can get a clarifier here:

HTH Super Clarifier
  • Effectively clears up cloudy water, leaving it crystal clear
  • Compatible with all pool types including saltwater & spas
  • Improves filter efficiency, removes debris, dead algae, dirt & doesn't impact pH levels

Step 8: Drain And Refill Hot Tub (Optional)

If you are still struggling with cloudy water after troubleshooting using this guide, you might be better off draining and refilling your hot tub. Over time, solids will be suspended in the water due to evaporation. This is why draining and refilling every 2-3 months is recommended.

Draining and refilling your hot tub may also be the most economical option. Continuously pouring expensive chemicals into your hot tub that won’t clear up is pouring money down the drain.

Frequently Asked Questions

Is It Safe to Get Into a Cloudy Hot Tub?

It is not safe to get into a cloudy hot tub because if it’s cloudy, there is a buildup of bacteria and other contaminants, or the pH level is off. The contaminants can cause skin issues and irritate the eyes. Work on getting your hot tub water clear before swimming.

Cloudy Hot Tub, But Chemicals Are Balanced

Sometimes you will have cloudy, hot tub water, but the levels are good. This can be several issues, primarily because there are leftover particles that are too small to filter or skim out. In this case, clean the filter, add enzymes, and add a clarifier. 

The other reasons listed above are poor filtration, the pump isn’t being run long enough or at a high enough speed, or the water isn’t circulating properly. However, more times than not, your hot tub is cloudy due to a chemical balance.

How Long Does it Take for Cloudy Hot Tub Water to Clear?

The time to clear cloudy, hot tub water may take anywhere from a few hours to a couple of days. It depends on the extent of the cloudiness and your spa’s equipment. Some tubs may need to be drained and extensively cleaned, whereas others may only need a new filter.

Can sweat cause cloudy spa water?

Sweat and other body oils can cause cloudy water in a hot tub or spa because it uses up the sanitizer and builds up in the jets. If left untreated, it will clog up the filter. Clean or replace the filter, balance the chemical levels, and add enzymes to clear this up.

How come my hot tub filter doesn’t clear the water?

Hot tub filters will not clear the water if the chemical balance is off. Another reason is that some particles are too small for a hot tub filter to capture. Filters remove small particles that are 5-10 microns. The particles that are too small to trap recycle back into the water, causing cloudiness. You can use enzymes and a clarifier to help clear the water.

How do I prevent cloudy, hot tub water?

Prevention is the best cure for hot tub maintenance. Weekly shocking and balancing the chemicals is the best line of defense. After the hot tub is used, especially if it’s a large bathing load, add sanitizer or clarifier to help the hot tub’s sanitizer clean the contaminants.

Here are some tips to prevent cloudy spa water:

  • Test the chemicals weekly
  • Add clarifier after adjusting the chemicals weekly
  • Shock weekly
  • Run the pump at high speed
  • Clean the filter monthly
  • Drain and refill every 2-3 months

Leave a comment