Eliminating Hot Tub Scale

Discovering scale in your hot tub for the first time can be an alarming and unpleasant experience. Scale has a sandpaper texture that grows on the surface of your spa, and it can also hide in less visible places like your water heating elements and plumbing system. It is formed when there is a buildup of minerals.

You’ll want to remove the scale as soon as possible to avoid damage from happening to your hot tub. In this blog, we’ll explain how to eliminate hot tub scale from the surface of the tub and prevent it from coming back.


The filtration system plays an important part of keeping your spa water clean and free of dirt, oils, and other contaminants. Clean your filter on a regular basis to maintain healthy water quality and overall water flow. Depending upon usage, plan on cleaning your spa filter every two weeks, or as often as weekly.


There are three main contributors that promote scale growth in your spa: high pH levels, high alkalinity and high calcium hardness. Without testing your spa water, you won’t be able to accurately fix the root of the problem. So, grab your test kit or test strips and let’s get started!

Referencing your water test results, use spa balancing chemicals to correctly balance your water. Always read all labels and instructions, and check with your hot tub manufacturer before applying chemicals.

pH: 7.2-7.6 ppm. Use pH increaser or decreaser.

Total alkalinity: 80-120 ppm. Use alkalinity increaser or decreaser. Some pH adjusters will also alter the alkalinity reading.

Calcium hardness: 200-400 ppm. Most spas are fine with calcium hardness levels up to 400pm. If it’s low, add a calcium booster. If it’s too high, and you’ll be refilling from a hard water source (such as a well), drain the spa and refill with the help of a pre-filter to remove excess calcium.

Sanitation: Keep sanitizer levels between 1.5-3 ppm for chlorine and 3-5 ppm for bromine.


Incorporate brushing to loosen up and remove some of the scale on the surface of the hot tub. If you have an acrylic hot tub, you’ll need to be more cautious and scrub gently to avoid damaging the finish. Look for brushes that are safe for spas and hot tubs. When in doubt, test a small, inconspicuous area first.


If the scaling is severe, you will need to drain your hot tub. If you haven’t emptied your hot tub in 2-4 months, take the time to do so now. Draining your hot tub correctly will remove all the existing bacteria and dissolved solids built up over time. If you’ve never drained your hot tub before, don’t worry - we’ve got an article for that!


Fill your hot tub and add a scale prevention product. The Leisure Time Defender Spa Scale Preventer is great for removing stains caused by calcium and utilizes a second-generation blend of organic polymers to actively prevent future scale and stains. If you have hard water, you can also try to soften it by using a water softener.

By regularly maintaining your hot tub and keeping the water properly balanced, you will be able say “GOODBYE” to hot tub scale! For best results, remember to test your water 2-3 times a week and clean the spa filter on a regular basis.

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Leslie’s makes every effort to provide accurate recommendations based upon current ANSI/APSP/ICC-5 2011 (R2022) standards, but codes and regulations change, and Leslie’s assumes no liability for any omissions or errors in this article or the outcome of any project. You must always exercise reasonable caution, carefully read the label on all products, follow all product directions, follow any current codes and regulations that may apply, and consult with a licensed professional if in doubt about any procedures. Leslie’s assumes no legal responsibility for your reliance or interpretation of the data contained herein, and makes no representations or warranties of any kind concerning the quality, safety, or suitability of the information, whether express or implied, including, without limitation, any implied warranties of merchantability or fitness for a particular purpose.