Can You Use a Hot Tub With Cloudy Water? (7 Dangers)

If you’ve just opened up your hot tub to find the water has turned cloudy, you might be tempted to have a soak regardless. But is cloudy water safe?

You should not use a hot tub when the water is cloudy. Cloudiness is a sign that the water isn’t clean and sanitary. The cause could be a dirty filter, high total alkalinity, a pH imbalance, low sanitizer levels, high calcium hardness, pump problems and airlocks, and a biofilm build-up.

Cloudy spa water can make you pretty sick, so in order to remedy the problem, we need to take a look at the seven possible causes.

1. Clogged and dirty filter

Why you shouldn’t use a hot tub with a clogged and dirty filter

Whenever you face an unexpected issue with water quality in your hot tub, the first thing you should check is the filter. Water quality issues can clog your hot tub filters as algae, and other contaminants build up on their surface.

If the filter is clogged and dirty, it won’t be able to filter out any impurities in the spa water, thereby leading to water clarity issues such as cloudiness. Since these Impurities result from living organisms like bacteria and algae, they can be very dangerous to your health. 

Not only are clogged filters risky to your health, but they can also damage your hot tub pumps. The damage occurs because the pumps would strain to pull water through these clogged filters.

Cloudy water can also occur when the filter isn’t positioned properly. In this case, the water bypasses the filter cartridge and continues to circulate unfiltered.

How to fix a clogged and dirty filter

Remove the filter and rinse with a chemical spray. If it’s been a while since you last cleaned the filter, it’s best to perform a 24-hour chemical soak.

If you can’t get the filter clean after soaking it in chemicals, then it’s time to replace it. You should also replace your filter every 12 months. If your hot tub is used a lot, the filter needs to be replaced more frequently.

Lastly, make sure you position the filter correctly when reinstalling it. The cartridge should be fully seated on both ends to ensure the water is forced through the filter pleats.

2. High total alkalinity

Why you shouldn’t use a hot tub with high total alkalinity

Hot tub water with a total alkalinity (TA) reading above 200 parts per million (ppm) is a likely cause of cloudy water in your hot tub. This is due to the TA creating a pH imbalance, which causes calcium scaling in the spa.

High TA levels can also cause the chlorine sanitizer to be less effective. And when the sanitizer can’t do its job effectively, bacteria multiply and cause the spa water to become cloudy. You don’t want to be in a hot tub with growing bacteria, as this can be risky to your health.

Total alkalinity is the buffer that prevents fluctuations in the pH level. High TA levels make it difficult to control your pH and keep it in range. Therefore, you should always test and adjust the total alkalinity before moving on to the pH.

How to fix high total alkalinity

To fix high TA in your hot tub, you need to test and lower the alkalinity. You can use test strips to carry out the test, but a test kit will give you the most accurate test results.

Collect a water sample from the hot tub and allow it to cool to room temperature before testing it. Add pH decreaser (sodium bisulfate) to lower the TA to between 100-150 ppm. Then let the water circulate for at least 15 minutes before testing it again.

3. pH imbalance

Why you shouldn’t use a hot tub with a pH imbalance

Another common cause of cloudy water in a hot tub is high pH. The water in your hot tub should have a neutral, stable pH to prevent health issues. 

Very high pH levels cause calcium not to dissolve properly, which leads to cloudy spa water. High pH can also cause eye or skin irritation. 

However, pH imbalance isn’t a direct cause of cloudiness but it affects how sanitizers and other chemicals work in your spa water. 

For instance, chlorine becomes highly reactive when the pH is low, causing it to deplete rapidly. Because all the free available chlorine has been used up, the chlorine sanitizer becomes ineffective in killing bacteria and other microorganisms in the hot tub water.

How to fix pH imbalance

The optimum range for pH in a hot tub is between 7.4 and 7.6. It is often recommended to keep the pH between 7.2 and 7.8, but it’s better to keep it within the optimum range to give yourself some breathing room in case things change unexpectedly.

To fix the pH imbalance, the first thing to do is to test the water using a liquid test kit. Collect a water sample from the hot tub and allow it to cool to room temperature.

Depending on your reading, you’ll need to add either a pH decreaser or pH increaser. After adding the appropriate chemical, let the water circulate for at least 15 minutes before testing the pH levels again.

4. Low sanitizer levels

Why you shouldn’t use a hot tub with low sanitizer levels

Chlorine is a powerful disinfectant, but it loses its effectiveness over time as it fights all the contaminants lurking in your hot tub water. 

When the free chlorine levels become too low, the sanitizer becomes ineffective and is unable to disinfect the water. The chlorine now available in the water is combined chlorine (also known as chloramines), which can lead to cloudiness in the spa water.

When the sanitizer level drops below 1 ppm, microorganisms like bacteria multiply faster than they’re being destroyed, resulting in cloudy water. This puts you at risk of contracting legionella (Legionnaires’ disease), E. Coli, and hot tub rash.

How to fix low sanitizer levels

If you use chlorine as your sanitizer, add enough to raise the level to within 1-3 ppm. 3 ppm is the optimum level for chlorine in a hot tub.

If you prefer to use bromine to sanitize your hot tub, add enough to raise the level to between 3 and 5 ppm. 5 ppm is the optimum level for bromine in a hot tub.

To give the sanitizer a boost, shock your hot tub water regularly. This is especially important if sanitizer levels have dropped suddenly or if the spa has seen a lot of use in a short period.

However, hot tub water may turn cloudy after adding chlorinated shock due to the many chemical reactions that are occurring, but this is perfectly normal. 

The water should turn clear again a few hours after adding the shock. You can also try using a non-chlorine MPS shock to avoid cloudy hot tub water.

5. High calcium hardness

Why you shouldn’t use a hot tub with high calcium hardness

Hot tub water with high calcium hardness levels will turn the water cloudy unless the alkalinity and pH are low enough to compensate.

If the calcium hardness reading of the hot tub is above 400 ppm, you’ll experience cloudiness and start to notice crusty, white scales around jets and other components of the spa, including inside the plumbing.

Calcium deposits cause filters to clog and provide an anchor for microorganisms. And we already know that clogged filters can cause cloudy water. The higher the spa water temperature, the more scale there’ll be. 

In addition, scale build-up in the pipes reduces circulation and increases pressure, causing the hot tub to take longer to heat up. Over time, the scale will also cause the heater to fail prematurely.

Not only can scale damage hot tub parts, but it can also cause discomfort to bathers. If you soak in a hot tub with high calcium hardness, you will likely experience eye and skin irritation.

How to fix high calcium hardness

Test the calcium hardness levels using test strips or a calcium hardness drop test kit (most accurate). The ideal range for total hardness in a hot tub is 175-250 ppm.

If the level is slightly above 250 ppm, perform a partial drain of the hot tub. It’s best to drain about half the water. If the level is way above 250 ppm, completely drain the hot tub and refill. 

In both instances, make sure to refill from a hose fitted with a pre-filter to help filter out many unwanted minerals from the source water. 

In addition, use a stain and scale control regularly to keep things balanced and prevent fluctuations in calcium hardness levels. This is especially important if you live in a hard-water area or you source your water from a well.

6. Pump problems and airlocks

Why you shouldn’t use a hot tub with pump problems and airlocks

There are several reasons your pump is causing the water in your hot tub to turn cloudy. The first reason is that you might not be running the pump long enough each day.

Another reason is that there could be an issue with the pump impeller. Because the vanes on the impeller are very small, they clog easily, which dramatically reduces the flow volume.

Lastly, cloudy water may occur if the impeller is broken. If the pump turns on, but the impeller isn’t moving, there’ll be no flow. And if there is no flow, it’s a sign of an airlock. A common effect of an airlock in a hot tub is malfunctioning or failure of the jets.

How to fix pump problems and airlocks

If you usually don’t run the hot tub pump for long, you would need to increase the runtime so that the spa water can circulate and filter properly. 

The pump should run for at least two hours every day. It’s advisable to run it at high speed because running at low speed can lead to ineffective filtration.

If there’s an airlock, you’ll need to shut the pump off and loosen the union on the pump to allow the air to escape. Once the water begins to leak, tighten it back up.

7. Biofilm in the plumbing

Why you shouldn’t use a hot tub with biofilm in the plumbing

Biofilm can turn hot tub water cloudy. However, it’s not so common and only occurs in extreme cases. Biofilm can form rapidly in hot tubs that have been sitting empty for a while. You may also notice foaming and slimy flakes floating on the water when there is a build-up of biofilm.

Biofilm is very acidic and can damage your pumps, heater, jets, and filter. It is also risky to your health as it can lead to Hot Tub Folliculitis (also known as Hot Tub Red Rash) and Legionnaires disease.  

How to fix biofilm in the plumbing

To remove biofilm from your hot tub, the first thing to do is to lower the pH to 7.2. Then use spa shock to raise the chlorine level above 10 ppm. The high chlorine level helps to eliminate bacteria and other microorganisms.

Next, use a line flush cleaner like Ahh-Some. Allow the cleaner to circulate around the plumbing for several hours or overnight so that it can remove all the biofilm. Once this is complete, drain the water and clean the empty hot tub thoroughly.

Joshua Milton

Joshua Milton is a seasoned hot tub enthusiast. With many years of experience in the industry, he offers valuable insights on hot tub maintenance, health benefits, and relaxation techniques.

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