How Long Does It Take to Clear a Cloudy Hot Tub?


There’s been many a time that I’ve pulled back my spa cover only to reveal white, cloudy water. Here’s what I’ve learned over the years about how long it takes to clear cloudy water.

It takes up to 24 hours for cloudy water to become crystal clear again after treatment. The amount of time it takes to clear can be reduced if you drain the hot tub and fill it with fresh water. Non-chlorine shock may clear cloudy water in 10 – 15 minutes if the clouding isn’t too severe.

In this article, I show you:

  • Whether it’s safe to bathe in cloudy water
  • How effective shock is
  • How to identify the cause and fix
  • How draining the water is sometimes the quickest option

Can I use my hot tub if the water is cloudy?

I know how frustrating it can be to have to wait around when all you want to do is take a relaxing soak. So is cloudy water safe for bathing?

You should never use a hot tub when the water is cloudy. Cloudy or milky water is a sign that there is a build-up of harmful bacteria in the water, so bathing in cloudy water has a real potential to make you sick. You must treat the water chemistry and wait until the water is crystal clear again before entering the spa.

There are many things that can cause spa water to turn cloudy, so locating the source of the problem isn’t always straightforward.

Saying that, the good thing is that all the causes have one thing in common: they’re the result of outside contaminants that haven’t been treated satisfactorily with sanitizing chemicals or proper water care and cleaning.

One of the main causes of cloudy water is caused by the bathers themselves, which is an unfortunate consequence and one that cannot be avoided.

Each time you use your hot tub, you introduce dead skin cells, sweat, and oils from your body. Even worse are care products such as soap, deodorant, hairspray, makeup, and lotions that find their way into the water from your skin.

Rather than seeing it purely as a negative, the water turning cloudy is actually a helpful sign that something is wrong and that it’s necessary to take action.

The only remedy is to adjust the water chemistry to make the water safe again for soaking. It’s important to remain patient when treating cloudy water. Don’t be tempted to use the spa until the water is crystal clear again.

Does shock clear a cloudy hot tub?

Spa shock can clear cloudy hot tub water. Chlorine-based shock works by breaking down organic waste that causes the water in your hot tub to turn cloudy and smelly. Non-chlorine shock activates free chlorine that kills bacteria and prevents the water from becoming cloudy.

You should shock your hot tub at least once a week. If your hot tub gets used frequently or is used by several people at once, you should use shock twice a week.

How long does it take for shock to clear a cloudy hot tub?

It takes up to 24 hours for cloudy water to clear after using a chlorine-based shock. It’s important to test the pH and sanitizer before entering the spa to ensure that they’re at the appropriate levels. After using non-chlorine shock, you should only have to wait 10 – 15 minutes before getting back in.

Why is my hot tub still cloudy after shock?

While it’s great that you’re using shock on a regular basis, sometimes it isn’t enough.

If the water is still cloudy after using shock, then it’s necessary to look elsewhere to locate the cause of the problem. Common reasons why the water remains cloudy after using shock are a dirty filter, high calcium hardness, high total alkalinity, high pH, high cyanuric acid levels, and lack of spa clarifier.

How to fix cloudy hot tub water

Read through all the potential causes to identify and fix the cloudy water in your spa.

Clean the filter

To clear cloudy hot tub water, the first thing to do is give the filter a thorough clean. Your spa filter isn’t able to filter out as many contaminants as it becomes clogged up with dirt and grime over time.

While some spa owners like to reduce chemical use as much as possible by using natural ingredients such as vinegar to clean their filter, I always recommend using a dedicated filter cleaner as it’s better able to clean and disinfect.

Remove the filter from its housing, give it a gentle rinse with fresh hose water, and submerge it in a chemical soakOpens in a new tab. for 24 hours.

Once complete, rinse off the chemical residue and use this specially designed filter combOpens in a new tab. between the pleats to remove all traces of dirt. Allow to air dry before replacing.

If you’re not able to get it clean using a chemical soak, then it’s time to replace the filter.

Another issue you may face is that tiny particles are often able to bypass the filter fibers as they’re just too small to be picked up.

Adding this spa clarifierOpens in a new tab. to the water binds tiny particles into large clumps so that they can be readily dealt with by the filter.

Check the alkalinity, pH, and calcium hardness

High total alkalinity causes carbonates to fall out of solution, resulting in fluctuations in the pH. A change in alkalinity and pH is another common cause of cloudy spa water. Test and check in the following order:

  1. Alkalinity: First, test and adjust the alkalinity levels so that they’re between 100 – 150 parts per million (ppm).
  2. pH: Now move onto the pH. The optimal range for spa water is between 7.4 – 7.6 pH.
  3. Calcium hardness: If you live in a hard water area or source your water from a well, then you may need to adjust the calcium hardness levels too.

When there is too much calcium in the water, it falls out of solution and turns the water cloudy.

Lowering the calcium level is achieved by adding calcium hardness decreaser. This helps to keep the calcium locked in solution.

Rather than buy each of these products separately, I recommend this balancer bundle kitOpens in a new tab. as it has everything you need for tackling cloudy water and other clarity issues. Purchasing a kit has the added benefit of saving you money and time over buying single bottles.

Check sanitizer levels

Ensuring that there is an adequate level of sanitizer in your spa is vital to fight against all the contaminants that are introduced with every use.

Microorganisms in your spa water are able to multiply at a faster rate than they’re being destroyed if you allow the sanitizer level to drop below 1 ppm, exposing you to legionella (Legionnaires’ disease), E. Coli, and hot tub rash.

Ironically, adding too much sanitizer can also cause the water to turn cloudy, so it’s important to ensure that your chosen sanitizer chemical is within the optimum range.

ChlorineOpens in a new tab.: Adjust the chlorine to 3 ppm. Accepted levels are between 1 and 3 ppm.

BromineOpens in a new tab.: Adjust the bromine to 5 ppm. Accepted levels are between 3 and 5 ppm.

Shock the spa

Over time, your sanitizer gets used up as it has to deal with all the contaminants in the water, causing cloudy water and problems with scum.

If you sanitize your hot tub with chlorine or bromine, then using a chlorine-based shock will help to keep the water fresh and clear.

It’s important to use a shock that has been formulated for use in hot tubs and not for swimming pools. I recommend this dichlor shockOpens in a new tab., which can be added directly to the water without having to dissolve it first.

It’s normal for the water in your spa to turn cloudy for a few hours after adding a chlorine-based shock. It’s simply due to the many chemical reactions that are taking place.

Non-chlorine shockOpens in a new tab. can also be used to treat water clarity issues. It activates free chlorine to kill bacteria.

Although non-chlorine shock doesn’t turn the water cloudy, it isn’t as effective as chlorine-based shocks as it doesn’t disinfect. However, it’s an effective oxidizer that’s well worth using on a weekly basis to get rid of organic contaminants.

Before adding shock, test the water to make sure the pH levels are where they should be. After you’ve allowed the shock to take effect, check the sanitizer levels before taking a soak.

Drain the hot tub

If you can’t get the water crystal clear, then the last resort is to drain all of the water from your hot tub. Draining a hot tub is sometimes the best option if it’s seen a lot of action in a short period of time, perhaps because of a hot tub party.

I always like to use line flush before I drain my hot tub water. Oh YukOpens in a new tab. clears all traces of nasty biofilm (another cause of cloudy water!) that might be lurking in the plumbing.

This gives me peace of mind knowing that I’m not going to have any issues whatsoever after I’ve filled and heated the hot tub with fresh water.

After draining, give the empty spa shell a thorough cleaning with this surface cleanerOpens in a new tab. and rinse thoroughly.

Unless you live in an area with incredibly soft water, you should fit the hose with an inline pre-filterOpens in a new tab. to reduce up to 98 percent of the impurities in the water. Pre-filters make balancing your water a lot easier, saving you money on expensive chemicals.

Did I cover everything?

I always try to provide the most relevant and up-to-date information I can in all of my articles. Saying that, feel free to shoot me an email using the contact form if you think this article is lacking in some way, or if you’ve been left with any doubts.

Thanks for reading and happy hot-tubbing!

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