High alkalinity can cause a range of issues with your hot tub, ranging from skin irritation to poor sanitation. However, it’s important to understand what alkalinity is, and how to keep it to the correct levels when maintaining your hot tub. In this guide, we’ll explain how to reduce alkalinity in your hot tub, and the problems it can help you avoid in future.

What is alkalinity and why does it matter?

Like acid, alkalinity sits as a rating on the pH scale. The pH scale measures how acidic or basic all chemicals are, with 0 being the most acidic, and 14 being the most basic (or alkaline). 7 is the neutral point of the scale, representing pure water at 25 degrees centigrade.

While acids are often seen as harsh chemicals, strong alkaline compounds can be just as harmful. Harsh basic chemicals include bleach, ammonia, drain cleaner, and more. Thus, if your hot tub’s pH is too high, the side effects can be severe, so it’s important to keep it well-balanced at all times.

Why alkalinity levels matter

High alkalinity in a hot tub is dangerous, as it can cause damage to your components, and to your body if you choose to bathe in it! Here are just a few of the ways that high pH can affect you:

Increased calcium scaling

Limescale becomes much more common in hot tubs with a pH of 8 or higher. These chalky deposits of calcium carbonate can clog up your jets, erode the chassis of your tub, and cause cloudy or foamy water. High alkalinity can also make your other hot tub chemicals more or less effective, throwing your whole maintenance routine into a spiral.

Reduced sanitiser efficiency

The chlorine compounds used in hot tub maintenance have a very high pH, with liquid chlorine reaching as much as 13 on the scale. If high alkalinity is affecting your hot tub, then sanitisers such as chlorine will be less effective. This means you’ll need more chlorine to counteract the effects, which will raise the pH even further, worsening the effects.

Skin irritation

Highly alkaline substances like bleach and ammonia are known irritants when they come into contact with skin, but high-pH water is the same. When bathing in water that’s too basic, you may experience itching, irritation, and a burning sensation in the eyes if any water touches them.

What causes high alkalinity?

There are a range of factors that can increase the pH of your hot tub. Here are just a few things that might be adding to your water’s alkalinity:

  • Sweat
  • Sunscreen or body lotion
  • Perfume
  • Too many chemicals

To avoid getting unwanted chemicals in your water, be sure to shower before getting into your hot tub.

Is it safe to go in a hot tub with high alkalinity?

Highly alkaline water can cause skin irritation and itching, with symptoms worsening at higher pH levels. The risk of damage to your body is too high when bathing in basic water, so avoid getting into your hot tub unless it’s at a safe level. A pH of 7.2 to 7.8 is typically accepted as the ideal range for bathing.

Determining your hot tub’s alkalinity

To find out what your hot tub’s alkalinity is, you should use pH strips. These will turn a certain colour (typically red or purple) depending on how acidic or basic your water is. This allows you to determine the alkalinity of your hot tub’s water, or how acidic it is if the pH is too low.

pH strips will typically let you measure other levels of chemicals in your hot tub’s water too, so it’s important to keep all of these balanced to appropriate levels. You can also purchase more expensive technology to measure your water’s pH electronically, such as using probes. While strips are cheaper, these methods tend to give measurements that are easier to read and are reusable compared to disposable strips.

How to reduce your hot tub’s alkalinity

Once you’ve identified an issue with your water’s pH levels, it’s easy to adjust them back to safe levels. Here’s a step-by-step guide to reducing your hot tub’s alkalinity:

  1. Find a suitable pH reducer – in a pinch, you can use household items with low pH such as white vinegar.
  2. Add the reducer to your hot tub’s water.
  3. Test the water, then leave it to circulate for 24 hours before testing again. Adjust the pH further as needed.

Maintaining your hot tub’s alkalinity

Having sorted out your tub’s alkalinity, you’ll need to stay vigilant for further changes to stop any issues from repeating themselves. Here are some ways you can control the pH of your hot tub:

  • Be sure to stay adequately stocked with both pH-decreasing and increasing agents
  • Test your hot tub’s water daily – pH strips are useful for this, but you can invest in a reusable electronic probe for more accurate readings.
  • Make sure to flush and replace your hot tub’s water every now and then to reduce the build-up of chemicals over time.

Learn more about hot tub maintenance with Platinum Spas

We hope that you’ve found this guide on managing your hot tub’s alkalinity helpful. Balancing your hot tub’s pH is a vital part of hot tub maintenance and one that you should never neglect to carry out. If you’ve not carried out regular checks in the past, there’s no better time to start than now.

Of course, you only need to worry about hot tub alkalinity levels if you actually own such an at-home spa system. Here at Platinum Spas, we sell a range of innovative hot tubs and swim spas. Contact us today to view one of our products or to speak to an expert in more detail.

High alkalinity in a hot tub FAQs

Still worried about high alkalinity in your hot tub? Here are a few common questions we answer about high-pH water:

Will alkalinity decrease on its own?

While your hot tub’s alkalinity will decrease on its own over time, it can have several knock-on effects, such as unclean water due to decreased sanitiser efficiency. It’s better to treat pH issues early before any damage is caused, and it’s easier to monitor changes to your water’s levels this way.

What neutralises alkalinity?

Alkalinity is neutralised through the use of acids. You should only use certain acids, however, as some are far too strong to safely use in a hot tub.

Does shock lower alkalinity in a hot tub?

You may be tempted to shock your hot tub to better balance its pH, but this doesn’t affect your hot tub’s alkalinity greatly. In fact, chlorine shocks can raise the pH of your water and make it even more alkaline. Non-chlorine shocks are much safer to use on tubs where chlorine or bromine are used for maintenance.

Does raising alkalinity raise pH in a hot tub?

Generally speaking, alkalinity directly affects the pH of your pool, but “total alkalinity” is a different measurement itself. Rather than looking at the strength of the basic chemicals in your water, this represents the concentration of these chemicals compared to the amount of water in your hot tub.

This means that certain chemicals will raise your pH and your total alkalinity in different amounts, so it’s worth paying attention to both. We recommend keeping your total alkalinity at a level between 80 and 120 ppm (parts per million) for the most efficient maintenance of your hot tub.

Sarah Watkins
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