Why Does My Spa Feel Like Sandpaper?


Sandpaper-like textures found in spas can most often be attributed to pH levels being too high within the water. In the occurrence of an elevation in pH levels, the calcium within spa water begins to precipitate out.

After doing so, the precipitated calcium begins to form on the surface of the spa itself. Beginning as a white powder, the calcium eventually forms into hard crystal structures that accumulate on the lining of the hot tub and feel like sandpaper to the touch. 

What is scaling in a hot tub?

Hot tub scaling is the build-up of minerals within a hot tub over a period of time. These various minerals are abundant in hot tubs and often look like little white clouds floating in the water.

However, the occurrence of scaling in a hot tub can be caused by a variety of things including:

  • hard water,
  • highly alkaline water,
  • water containing iron,
  • water containing high levels of calcium,
  • or contaminants such as body oils and lotions.

The problem is that the minerals collect and clump together often piling on ledges and shelves and blocking filters. This creates damage to the hot tub lining and filters. In addition, the presence of scale makes using a hot tub unenjoyable overall. 

How do you get rid of scale build up in a hot tub?

In order to rid a hot tub of unwanted scale build-up, the affected areas should be thoroughly covered with a hot tub scale remover.

This product actively works to break down the scale and remove it from the sides and fixtures of the hot tub as it begins to disintegrate. The scale then moves towards the filters and out of the water supply. However, it is important to remove and thoroughly clean the filters in order to prevent any scale from finding its way back into the hot tub water or causing the filter to quit working. 

Finally, if the scale remover does not work on its own, the hot tub should be drained of all water. Then, the scale remover should once again be generously applied to any problem areas. From there, any remaining pieces of scaling should be manually broken off of the hot tub. 

How do I get rid of scale in my hot tub?

As previously mentioned, getting rid of and preventing scale in a hot tub comes down to maintaining proper cleaning routines. However, if scale does accumulate, it can be removed by applying a scale remover product.

Typically, this will cause the scale to break up on its own, but if the build-up is immense, it may require a bit of manual effort to remove the scale from the sides of the hot tub in question.

Once a hot tub is clean, scale can be prevented from accumulating by regularly cleaning the hot tub, periodically draining all the water from and refilling the hot tub, maintaining properly functioning filters and replacing them when needed, testing the pH and alkalinity of water, and avoiding the use of any lotions, oils, or bath bombs that may add contaminants to the water when one is soaking in the hot tub. 

What causes scale buildup in hot tubs?

The most common causes of scale buildup in hot tubs can be attributed to either deposits of calcium scale or biofilm being present within the water.

For instance, calcium deposits accumulate when pH levels are high and there is an excess amount of calcium located in the hot tub’s water.

Owners can easily spot calcium deposits in their hot tubs as they appear as white clumps within a tub’s water. Additionally, it should be noted that all hard water has a high level of calcium and is a common culprit for deposit buildup.

Meanwhile, biofilm is the result of a buildup of materials that are shed from users of a hot tub such as oils, lotions, dead skin, and more. The film created is known as white water mold.

Furthermore, biofilm most commonly forms when a hot tub has been left unused for a significant period of time and has not been cleaned properly. The warmth of the hot tub provides a perfect environment for mold to form which results in the visible, white film. 

How do you stop calcium build up in a hot tub?

The first step to preventing the build up of calcium within a hot tub is to remove any existing calcium deposits. Once the hot tub is cleared and clean, the most important step to preventing any further issues with excessive calcium buildup is to maintain regular and thorough cleaning routines including the sides of the hot tub, the jets, and the filter.

It is also important to remember to change the filter out when needed. 

Additionally, if hard water is being used to fill the hot tub, it is wise to use a high-quality filter and a water softener to reduce the amount of calcium present within the water supply. Doing so will lessen the chance of accumulating scaling, especially if other proper maintenance methods such as a cleaning routine are put into place. 

Finally, frequently checking the pH balance and alkalinity of the water within a hot tub may serve to better prevent calcium buildup. The pH of a hot tub should be between 7.4 and 7.6, and the level of alkalinity should be between 80 and 120 parts per million (ppm).

Any pH or alkaline levels outside of these ranges can lead to quick calcium buildup. Luckily, products to test and restore these levels can be easily purchased.

Overall, the secret to maintaining a clean, safe, and enjoyable hot tub comes down to proper maintenance. Owners should ensure that they are using appropriate cleaning methods and chemicals, frequently testing the water’s pH levels, and limiting the number of foreign items and chemicals that come into contact with the hot tub.

However, if proper care is put into place, the accumulation of scale should be kept to a minimum and will be easy to prevent and maintain.

Editorial Staff

I'm Adnan Sabanovic, the guy behind Hot Tubs Report. I've had a chance to enjoy hot tubs last few years and have really become interested in owning one of them. Nearly every weekend you'll find me spending time with my family or playing sports. If I am not doing that then I'm here writing about tubs on Hot Tubs Report. This blog is a research for my first hot tub which I decided to document and share publically so others can benefit from it as well.

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