Can You Use a Hot Tub With High pH? (Know the Dangers)


Having to constantly maintain your hot tub water can quickly become a real nuisance. So if all you want is a relaxing soak, but the water pH is high, you’re left wondering whether it’s safe to use a hot tub with high pH.

Never use your hot tub if the pH is too high. A pH higher than 7.8 is too alkaline and will harm you and your hot tub. High pH causes a build-up of harmful bacteria and irritation to your face and skin. Over time, high alkaline water causes a build-up of scale that damages jets, filters, pipes, plugs, heaters, and pumps.

There are several reasons why your water has a high pH, and it might be a sign of a bigger problem. Before we look into that, I want to show you in more detail the dangers of high pH water.

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

If the water in your hot tub has a pH that measures outside the required range of 7.2 – 7.8, both you and your hot tub are at risk of health issues and damage.

High pH effects on your health and well-being

One of the worst things about bathing in water with a high pH is that it causes itchy skin, burning eyes, and irritation in the nose and throat. If you’ve ever swum in a swimming pool that was heavily chlorinated, you’ll know exactly what I mean.

When the pH level rises in your hot tub, it also has a detrimental effect on the disinfectant properties of chlorine (or whichever disinfectant you use).

For example, a pH level above 8.0 results in chlorine barely being 20 percent effective, and a level of 8.5 or higher means that the chlorine’s effectiveness is way under 10 percent.

Because the disinfectant isn’t able to do its job, the water becomes contaminated, which can potentially lead to a variety of illnesses caused by the build-up of bacteria and algae.

Frequent use of a hot tub with high pH could potentially result in nausea, stomach cramps, vomiting, and gastrointestinal upsets, allergic reactions, or breathing difficulties.

High pH damaging effects to your hot tub

High pH levels in your hot tub caused by a build-up of scale cause no end of problems inside the jets, filters, pipes, plugs, and other components.

The build-up restricts water circulation, causing a reduction in water pressure. This puts a lot of strain on your hot tub equipment and could cause the heater and pump to fail prematurely.

If the issue is not addressed quickly enough, scale build-up on the pump’s impeller may cause it to seize up, resulting in a pricey replacement job.

Another issue of high pH is that the water will turn foamy or cloudy from scale build-up. Limescale disposits will occur in and around the components inside your hot tub, which is something you’ll recognize if you live in a hard water area.

If left untreated for long enough, you might even notice white, chalky flakes coming from the jets. While these issues aren’t harmful to your health, it’s very unpleasant to look at and will definitely make it difficult for you to relax in your hot tub.

High pH creates extra running costs

One other issue you might not think of is the effect on your pocket. Keeping your hot tub sanitizer levels where they need to be is a tricky task if the pH is too high.

You will end up using a lot more bromine or chlorine than you would otherwise need if your hot tub water were in the appropriate pH range, meaning unnecessary expense.

And even if you use lots of sanitizer in high pH water, it still might not be enough to get rid of the unsightly problem of cloudy water.

What causes pH to rise?

There are a number of reasons why the water in your hot tub has a high pH. These include:

  • Total alkalinity too high
  • Too much shock
  • Water source is naturally more alkaline
  • Carbon dioxide build-up
  • Too much pH increaser

Total alkalinity is too high

The primary reason for a high pH level is very high levels of total alkalinity (TA). If the TA is high, then the pH is most likely high too. The TA is the first thing you should check if the pH level is higher than 7.8.

Total alkalinity is the buffer that keeps the pH in the acceptable range. When the TA is at the appropriate level, it works to prevent fluctuations in the pH.

If the total alkalinity is not within 80 to 120 parts per million, it cannot effectively buffer the pH to stay at the required range of 7.2 to 7.8.

You must always make sure that you have the correct levels of total alkalinity first before you attempt to address the levels of pH. This goes for both when the pH is too high and when the pH is too low.

Make sure to use fresh, high-quality test stripsOpens in a new tab.. It’s well worth mentioning that excessively high chlorine or bromine levels can result in false pH and TA readings.

For the most accurate readings, I recommend this complete water test kitOpens in a new tab. by Taylor Technologies.

The wrong type of shock

While some may think that shocking the water will lower the pH, the opposite is actually true. The chemical we call pool or hot tub shock is essentially concentrated chlorine.

Using liquid chlorine or household bleach, which both use calcium hypochlorite as their active ingredient, dramatically increases the pH level of your hot tub water, as well as changing the chlorine levels.

The significant rise in pH levels after adding calcium hypochlorite is due to how it breaks down combined chlorine (chloramines) while increasing free chlorine.

Liquid chlorine should only ever be used in swimming pools. For hot tubs, make sure to use dichlorOpens in a new tab. (sodium dichloro-s-triazinetrione) to avoid throwing off the pH.

As an alternative, you can use chlorine-free shockOpens in a new tab., which has a neutral pH and won’t affect any of your hot tub’s chemical levels.

When you use shock, the pH should be between 7.1 and 7.3 for maximum potency. If you shock a hot tub outside of this range, not only will you waste a significant amount of chlorine, but you will also end up with cloudy water.

Also make sure that you add the shock correctly to avoid bleaching out your liner, causing cracks and leaks in the base of your hot tub.

Water source is naturally more alkaline

The majority of homeowners use their mains water supply to fill their hot tub. Depending on where you live in the country, it might be that you have hard water that has a high pH level.

The combined amount of calcium and magnesium is known as the water’s total hardness. The recommended total hardness level should be between 175 and 250 parts per million (ppm).

If the total hardness of your water is higher than 250 ppm, you’ll need to purchase these bottles of descalerOpens in a new tab. and this Camco hose filterOpens in a new tab..

I come from a part of the country that has particularly hard water, so I always use this line flushOpens in a new tab. to get rid of scale and gunk in the plumbing before I drain my water each quarter.

Carbon dioxide build-up

Because hot tubs generate a lot of bubbles and run at high temperatures for a prolonged period of time, the combination leads to the creation of carbon dioxide gas. When carbon dioxide builds up, the pH levels go up with it.

To combat the problem, hot tub owners need to carefully add this pH minusOpens in a new tab. to lower their hot tub’s pH levels. Take care to add a small amount each day until the pH has come down to between 7.2 to 7.8. Adding too much too quickly can turn the water too acidic.

Too much pH increaser

If you’ve read through this list and you’re still baffled as to why your hot tub has a high pH level, then it could have simply been caused by adding too much pH increaserOpens in a new tab.. It’s necessary to use pH increaser when the pH levels fall below 7.2.

It’s a delicate balancing act to achieve the required range, which causes many to overestimate the amount of pH increaser necessary to bring the water back to the required pH levels.

Just as when using pH minus, care also needs to be taken by adding pH increaser in small quantities.

Constantly chasing pH levels is sign of a bigger problem

Generally speaking, once the pH levels have been set to the safe range of 7.2 to 7.8, there shouldn’t be huge fluctuations either up or down.

If you’re constantly having to chase the pH levels around to get the optimum levels, then the easiest thing to do is to start again by draining the hot tub and adding fresh water.

24 hours before you drain the water, add this line flushOpens in a new tab. and run the hot tub to clean out any build-up of gunk in the plumbing.

Make sure not to skip this step as it’ll remove whatever is causing the fluctuations. After you’ve drained all of the water, give the inside of the hot tub a thorough cleaning.

Constantly having to test your water isn’t much fun, which is why water conditioning systems such as Silk BalanceOpens in a new tab. are increasing in popularity.

Once you’ve got the pH and TA levels in the optimum range, Silk Balance ensures that the levels are locked in and stay that way for four months.

With Silk Balance, you get peace of mind knowing that there’ll be no nasty surprises to both you or your hot tub. Less time fiddling with water chemistry and more time relaxing in your hot tub. Perfect.

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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