6 minutes

hot tub water chemistry

Why Hot Tub Water Chemistry Matters

Things might feel a little complex when you start trying to understand what hot tub water chemistry is, what it does, what it entails and what you need to be aware of!  Worry not, Oyster is available to help!  When you buy a product from Oyster, you will be given training, a step-by-step guide with pictures, and information on how to both manage your water chemistry.  A chemical starter kit is always provided and is inclusive with a hot tub or swim spa purchase from Oyster.  We will also schedule periodic courtesy phone calls throughout the first year too, just to make sure you are happy and comfortable with all aspects of your product. hot tub water chemistry

What is water chemistry?

Simply put, water chemistry is the process of balancing and maintaining the correct total alkalinity and pH and bromine levels of your hot tub water.  Correct water chemistry feels and looks good and protects your spa shell and equipment, no doubt prolonging its lifespan.  As your hot tub is in a changing temperature environment, its chemical balance is constantly changing and it’s therefore really important to keep your water safe and tested regularly.

Unfortunately, if you are not balancing the water in your hot tub, this can lead to problems, which may include:

  • Scale forming
  • Cloudy water
  • Uncomfortable bathing
  • Ineffective sanitiser

hot tub water chemistry

What you need to monitor?

Let’s first look at what needs to be monitored within the hot tub water chemistry mix and the levels you should look to be achieving:


  • PH levels – between 7.2 and 7.6

pH is a scale for measuring acidity and alkalinity (0-14) and must be maintained.  If, at any time, it reads below the recommended 7.2, then the water is too acidic, which could potentially cause irritation and eye soreness.  If you get a reading above 7.6 the water is too alkaline, which can contribute to cloudy water and scale build up.


  • Alkalinity – between 80 – 120

Alkalinity is the process of measuring the amount of dissolved alkaline substances in water and it helps to control pH levels, so must be balanced correctly. If alkalinity readings are too high or too low this will affect the balance and hardness of the water.  Essentially, it acts as a ‘buffer’ for the pH.


  • Sanitisation – between 3.0 – 5.0

Sanitisation is essential for hot tubs.  Sanitisers are chemicals which are used to kill bacteria in your spa water. There are many types of sanitisers, however Oyster recommend bromine, as it is a less abrasive sanitiser.  It also has a lower pH than chlorine, making it a little easier to keep the water balanced, it lasts longer and it’s gentler on your skin.

hot tub water chemistry

What chemicals do I need?

So, now you know what needs to be monitored in relation to hot tub chemistry!  To enable you to obtain a good water balance and keep your chemistry correct, you will then need to look at the products needed :

  • Hot tub sanitiser – kills any present bacteria in the water.
  • PH Increaser – for when your water is too acidic.
  • PH Decreaser – for when your water has high alkaline levels.
  • Alkalinity Increaser – for when your water has low alkalinity.
  • Test strips – to determine the current chemical levels in your water. It reads sanitiser, pH and Total Alkalinity.

hot tub water chemistry

We will talk about chemicals in more depth in other articles, but the above are the must have’s for you to be able to keep your hot tub safe and healthy.  Please feel free to have a chat with our customer service team at any time if you are unsure about how to work your hot tub chemistry, we are happy to share our expertise with you.

With Oyster Pools & Hot Tubs, a chemical kit is always included with your hot tub or swim spa purchase and you will receive training and a water chemistry guide, so that you can quickly understand and perform the necessary checks and maintenance required yourselves.

Oyster Pools & Hot Tubs also recommends the use of O-Care.  O-Care is used to prevent build up of sediment in your hot tub, meaning that the chemical elements of water chemistry are working all the more effectively and able to do their job.

O-Care also contains a high-quality mix of minerals, keeping your water softer and crystal clear.  Great for those of us with sensitive skin in particular, but hot tub users really notice a difference, in that their skin feels soft and clean after their hot tub session.

We hope this has given you at least the basics on hot tub water chemistry and again, don’t worry, once you know how, it’s easy!

Please feel free to browse our articles on Hot Tub Operation to read more about care and maintenance of your product.



  Get In Touch

    Feel free to contact us at any time – we are always happy to help!

  01291 690 614 / info@oysterpools.co.uk


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