Balancing Hot Tub Alkalinity & PH

PH and Alkalinity are one of the most common areas of confusion for many hot tubbers and the risks associated with unbalanced water can damage your hot tub so it is a very important to get right. Questions such as "what is the difference between alkalinity and PH?", "Why does PH matter in my hot tub?" and "How do I raise alkalinity in my hot tub?" are the most common and will be answered below. 

What is Total Alkalinity?

Total alkalinity (TA) is the measure of the capacity of water to neutralise acids. It is different to PH. It is measured by parts per million rather than a scale like PH. Alkalinity is important as it acts as a buffer when balancing PH. If your alkalinity is out, then it will be very hard to balance your PH level. In fact it is a good idea to balance your Alkalinity before doing anything else as this may allow your PH to fall into line too and will make balancing PH much easier. Your Alklainity level should be between 80-120ppm.

What is PH and Why is it Important?

So once you have balanced your TA, the next step is to use a test kit or strips to check your PH level. PH is the measure of how acidic or how alkaline your water is. 7 is the neutral PH level but in your hot tub you want to aim to get your PH between 7.2 and 7.8. If you do not do this you may in for some nasty and potentially costly suprises!

Potential Issues with Low PH:

  • Poor Sanitiser Efficiency. Using lots of chlorine to not much effect and adding risk to bathers.
  • Corrosion of hot tub components due to the acidic nature of the water.
  • Itchy dry skin and eye sting.

Potential Issues with High PH:

  • Poor Sanitiser Efficiency. Using lots of chlorine to not much effect and adding risk to bathers.
  • Scale build-up on the spa surface and on components.
  • Cloudy or dull water and foaming!

How to Balance PH & Alkalinity

Balancing your PH and Alkalinity follows the same concept for both. If your levels are low, add increaser, if your levels are high, add reducer! The only difference is what chemicals you need to use. 

Lowering PH & Alkalinity Levels

If your PH and/or Alkalinity is high, you need to add a PH Minus to reduce these levels.

  • Do this gradually. Add the correct dose of PH Reducer, then run the jets and re-test in an hour or so and see if you need to reduce further.
  • PH Minus is the sole chemical used to reduce PH and Total Alkalinity in your hot tub. 

Raising PH Level

If your PH is low, you need to add a PH Plus to increase these levels.

  • Do this gradually. Add the correct dose of PH Increaser, then run the jets and re-test in an hour or so and see if you need to reduce further.
  • PH Plus will increase your Alkalinity level slightly too so keep an eye on this as remember Total Alkalinity is the buffer to allow your PH to be set.

Raising Total Alkalinity Levels

If your TA is low, it is most effective to use TA Plus to increase this level. PH Plus will increase your TA as mentioned above, but it will do so at a slower rate.

  • As with all other adjustments, remember to do this gradually so that you don’t increase TA levels too high resulting in the need to bring these down again. 

Does the balancing ever end?

Generally speaking, once your levels are set they should stay roughly within range however lots of factors impact this including other chemicals added to your hot tub, bathers, air injection into your jets and more! Many users are increasingly opting for water conditioner systems like Silk Balance, which offer an easy way to keep these levels locked in once set, this allows you to enjoy hot tubbing and take a day off from chemistry! If you opt for a water system like Silk Balance, you allow the natural formula to lock your PH and Alkalinity into place, protecting you and your hot tub from unbalanced water.

Common FAQ’s

I use Chlorine Tablets (Trichlor), why is my PH always low?

This is a very common question and the answer is quite simple, Trichlor Chlorine Tablets are acidic by nature and therefore as they sit in your dispenser or filter, they are constantly lowering your PH. At Happy Hot Tubs, we recommend Chlorine Granules as a default sanitiser as it is more PH neutral and prevents this issue. Bromine is also more PH neutral than Chlorine Tablets.

Whatever I do, I cannot get my PH correct - help!

Firstly, check your alkalinity. If your PH is hard to set, then TA may be causing the difficulties in setting your PH. Secondly, how old is your water? If your water is 3-4 months old, it is probably due a water change as the TDS (Total Dissolved Solids) have got too high. TDS is the measure how much ‘dissolved stuff’ is in your water; this includes all chemicals you add and anything taken into the hot tub by bathers. Once this reaches a point, you will find it very hard to get your sanitiser or PH/TA levels right. It may also be worth checking the expiry date/quality of your test kit.

Does PH Plus, Minus and TA Plus Vary in Quality?

The chemical formula of these products is quite basic but we have seen some poor quality batches on the market in the past. These are generally weaker and therefore you use a lot more to balance your levels. All chemical products sold by Happy Hot Tubs, including our own brand come from high quality UK suppliers so you can trust everything you see available for sale on our site to be of the highest quality.

Does PH Plus or Minus have an expiry date?

The answer to this is the same for all chemicals. While we don’t really recommend digging out some 15-year-old PH Plus or Minus to use in your hot tub, if it has been stored in a cool dry place and hasn’t caked badly, then it is likely to be absolutely fine to use.