Updated on 11/07/2022 by Nathan Bull

Is your hot tub water looking cloudy or murky?

It’s a common water care problem we see all the time, and the good news is it’s usually a pretty easy fix. It’s important to note that there can be a few possible reasons it can happen. We’re going to look at the most common ones, how to treat them, and how to prevent them.


How to Clear Cloudy Water

In most cases, cloudy water is cleared up with your sanitizer (chlorine or bromine). Here are the steps you should take when using chlorine as your sanitizer - bromine will be a similar process, just follow the directions on the back of the container instead when chlorine is mentioned.


  1. Increase your filter setting to 24 hours
  2. Test and balance your water
  3. Rinse or clean your filters
  4. Add two capfuls of Spa Shock and run pumps with the cover open for 20 minutes
  5. Add 30g (2 tablespoons) of chlorine per 1000L and continue to run pumps with the cover open for another 20 minutes
  6. Retest water in 6 hours (or the next morning if adding chlorine at night)
    • If chlorine is 1ppm or less, repeat steps 5 and 6
    • If chlorine is between 1 and 3ppm, add 15g per 1000L and repeat step 6
    • If chlorine is between 3 and 5ppm, add 15g of chlorine
    • If chlorine is above 5ppm, do a final water test the next morning


The goal is to continue to add sanitizer to your hot tub until it remains high for at least 24 hours - this indicates all contaminants have been destroyed. You may need to repeat the process server times.


Rinsing your filters at least once or twice daily will help clear up the cloudiness faster. It can sometimes take up to a week for cloudy water to clear fully, but you should notice differences overnight. Once your chlorine has remained high for 24 hours, you can add Spa Clear to help remove the cloudiness faster.


Pro tip: The longer the hot tub has less than 1ppm of chlorine, the more chlorine you’ll use because the bacteria causing the cloudy water will grow back if chlorine falls below 1ppm. Do not wait too long to retest your water.


If you’re still having issues with cloudy water after following these steps, take a look at some of these other possible reasons and how to treat them. In particular, if your cloudy water also feels slimy and is accompanied by discoloured, oily foam or large white flakes, see biofilm.


Reasons for Cloudy Water

Improper sanitizer levels (Chlorine or Bromine)

The most common cause of cloudy water is low sanitizer levels in your hot tub. However, this doesn’t necessarily mean you’re not adding enough chlorine or bromine; a few things can influence it.


High pH levels

When pH levels in your hot tub are too high, they can severely impact sanitizer effectiveness. A pH reading of 8.0 will make chlorine about half as effective and 8.5 almost entirely ineffective - this is one reason why it’s essential to test your water before adding chlorine.



Although this only represents a small percentage of cloudy water cases, it’s important to be aware of it. Like high pH levels, excessive phosphates can significantly impact your sanitizer demand. Hygiene products like soaps, shampoos, conditioners, make-up, and skin care products can gradually add phosphates to your spa, but they could also be added from tap water when you fill your hot tub.


If you’ve tried our other steps and suspect you have excessive phosphates, head into a local pool or hot tub store and request a phosphate test. Fortunately, if you know you have excessive phosphates, it’s easy to control using a phosphate remover like No Phos.


Dirty or Clogged Filters

If a filter is dirty or clogged, it’s unable to take any additional contaminants out of the water. Cleaning your filters will help clear up cloudiness, but you’ll likely need to do this a few times as there may be a buildup they need to clear out, which will cause them to become full again. Filters that are 8-12 months old or damaged will need to be replaced.


High Total Dissolved Solids (TDS)

TDS measures the total amount of solids dissolved in your water - including minerals, metals, salts, phosphates - pretty much anything that dissolves in your hot tub water. TDS is one of the main reasons you must drain your hot tub every 2-4 months.


When TDS reaches 2000-3000ppm, it becomes difficult to prevent water clarity issues, and more chemicals are needed to maintain a healthy spa. Another indicator of high TDS is difficulty controlling alkalinity. You can check your TDS using a TDS meter, which you can find at local hardware stores or Amazon.



Although cloudy water can sometimes be a sign of biofilm, it’s usually accompanied by other issues - unusual odour from the water, oily discoloured bubbles, or large white flakes. Biofilm can occur when a spa is left without sufficient sanitizer over some time. If you suspect biofilm, you’ll want to address it immediately - see our article on how to get rid of biofilm.


Hard Water and Metals

Hard water can contribute to cloudiness because of the increased TDS. Your total hardness levels should be between 150-250 ppm. If you’ve got hard water, read out blog post 6 easy steps to control hard water.


How to prevent cloudy water

The primary way to prevent cloudy water is by testing and cleaning your water regularly. Although pH and alkalinity can play a role in cloudiness, your sanitizer (chlorine or bromine) levels are the main ones to watch out for. Clean your water by periodically rinsing and cleaning your filters and removing large debris with a net. If you’re concerned with hygiene products like soaps and oils in your hot tub, consider using a Zorbie.

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