Limescale in hot tubs

If your hot tub shell and jets feel rough like sandpaper then you most likely have an issue with limescale in your water. If untreated and left unresolved for long periods, this can have a negative impact on components with pumps and heaters failing. But don't worry, in this article we will help you understand why this occurs, how to remove it from your hot tub and how to prevent scale from building up in your hot tub in the future. 

What is Limescale? Why is it all over my hot tub?

hot tub heater damaged by limescaleLimescale is a hard white or grey deposit that is composed of calcium and magnesium. When you have high levels of hardness in your hot tub water, combined with high PH, you may start to see calcium deposits on your hot tub shell, jets and plumbing. One of the most common ways this appears in a hot tub is by a thin layer sticking to your hot tub shell, causing your smooth shell to feel rough like sandpaper. In more subtle cases, you may only see calcium deposits when heaters or pumps fail and they need replacing. 

How to Remove Scale from Your Hot Tub

There are two main ways to remove scale from your hot tub. For more severe scaling, draining the hot tub and applying a no scale product directly to the affected areas can help loosen off any deposits. In lighter cases, by balancing the PH, adding an anti-scale chemical and cleaning your filters, you can break down the limescale and remove it without having to drain the water. In some cases, a combination of both options also works. 

Option 1 - Balance PH, Add Anti-Scale and Filter Clean

  1. Ensure your PH level is between 7.2 and 7.8, for the purposes of loosing scale from components and the hot tub shell, it is ok to temporarily drop the PH a bit lower than the recommended range (7-7.2) to help break down stubborn scale. Please see our guide on balancing PH and Alkalinity
  2. Ensure your jets are on and then add anti-scale directly to the hot tub water. Run the jets for 5-10 minutes. The water may go cloudy temporarily. 
  3. Wait 12-24 hours later and then clean your filters thoroughly with a filter cleaner. 
  4. If there are still scale deposits then you may need to add further anti-scale and perform addiitonal filter cleaning.

Option 2 - Drain, Apply Anti-Scale, Scrub and Rinse

  1. Prior to draining ensure your PH is between 7.2 and 7.6. It is ok to temporarily drop the PH a bit lower than the recommended range (7-7.2) to help break down stubborn scale.
  2. Drain your hot tub fully. 
  3. Wearing protective gloves, apply No Scale to a sponge or scrubber and rub into a small area. Leave for 10 minutes, rinse thoroughly and check for impact.
  4. If happy with the test patch above, apply more liberally to affected areas, leave for 10 minutes and rinse thoroughly.
  5. Rinse thoroughly and remove the excess water from your hot tub. 
  6. You may need to re-treat if there is stubborn scaling. 
  7. Once happy that most of the scale has been rinsed off and removed, re-fill your hot tub.
  8. Once full, ensure your PH is 7.2 to 7.8 and add a dose on No Scale as a preventative measure for any scale deposits left in the pipework.

How to Prevent Scale Build-Up in the Future

Focus on PH

You do not have to remove hardness from your water. That process is time-consuming and costly (see below). But if you are going to leave your water with hard water then you must keep a close eye on PH levels. PH should be kept between 7.2 and 7.8 in order to prevent scale from suspending on to your shell or components. 

Add Anti-Scale Weekly

There is no harm in adding Anti-Scale weekly to your hot tub. This belt and braces approach offer some prevention and breaks down any scale that may have formed, even smaller deposits. 

Use a Water Conditioner

Water conditioners like O-Care and Silk Balance offer advanced softening of your water, as well as, in the case of Silk Balance, the buffering of PH levels. These products also prevent scale deposits from sticking to pipework or components, helping them get filtered out and protecting your hot tub. These products are simple to use, by adding a dose weekly to your hot tub water.

Fill Soft to Remove Calcium Hardness

This is one of the more costly approaches and it is not wholly necessary. However, if you do wish to remove calcium hardness before it gets to your hot tub you can fill soft by using a portable water softener. Filling a hot tub soft is a requirement for those on salt systems to prevent the risk of calcium forming on the salt cartridge.