Hot Tub Scaling

Written by Greg Wednesday, 21 October 2009 17:43

One of the most common maintenance issues we get asked about is the formation of scale inside a hot tub.  Before I get to the ways of preventing scale from forming or how to get rid of it once its there, let's look at what scale is and why it can form in the first place.

Scale is simply the precipitation of dissolved minerals from your water, such as calcium and magnesium.  In other words calcium and magnesium minerals come out of the water and form a solid coating on your hot tub surfaces.  There are two main factors at work here.  First is the water hardness, which is a measure of how much mineral content there is in your water.  For example, well water has a much higher mineral content and is described as being "hard".  Thus, there is more potential for scale formation when you start with hard water.   The second factor is the pH of the water.  pH is a scale of acidity with 7 being neutral.  As the pH of water gets high, say over 8, the water becomes alkaline and the minerals in the water start to come out of solution and coat the hot tub.

What happens next is that small strips of the scale from inside the hot tub plumbing peel off and start to float around in the water.  These pieces are usually brown or beige in colour and almost look like skin.  Your filter will snare a lot of these pieces but it usually continues until some corrective action is taken.

Understanding what scale is and how it forms allows us to prevent it.  For many hot tubbers hard water is a reality, myself included, so the main factor to concentrate on is the pH of the water.  It is essential that you keep the water's pH within the proper range of 7.2 to 7.6.  This will prevent scale formation in the first place.  Secondly, I recommend that you use a Stain and Scale Control product that helps prevent scaling by reacting with the minerals in the water.  However, using a Stain and Scale product alone is insufficient to eliminating scale...you must also keep the pH balanced.

Of course we get asked about scaling a lot after the fact and so we need a way to remove the scale that has formed.  The best way is to lower the pH of the water so that it becomes acidic allowing the calcium and magnesium scale to dissolve and reenter the water solution.  The easiest way to do this is by using a de-scaling cleaning product.  We sell one called Cal Pro that you add about an hour before draining the water and then starting up again with a fresh fill.  In severe cases, you may have to use Cal Pro multiple times before you eliminate the scale build-up that has occurred.

Awareness of how and when scale can form will help you prevent scaling from occurring in your hot tub, and will help you eliminate it if it has already occured.  Contact our service department if you would like more information.