Has the interior of your spa developed a gritty hot tub scale, often described to feel like sand paper? This is actually a very common problem in hot tubs, so know you are not alone.
What causes “sand-paper” hot tub scale?
There are a few different things pertaining to your water chemistry that can cause this kind of hot tub scale. First is your pH, pH in your spa should be maintained at 7.4-7.6. Warm water mixed with high pH can cause calcium to build up and settle on the surface of your spa.
Calcium hardness in your water can also contribute to this type of hot tub scale. Often the calcium comes from initially filling the tub with a water source that is high in calcium.
Alkalinity is the third factor of water chemistry that can cause this type of hot tub scale. Total alkalinity is a measure of buffers in your water that help control your pH levels. High alkalinity will normally result in high pH which can cause scale to form. Total Alkalinity levels should be maintained between 125-150 parts per million (ppm).
As these are the main causes of hot tub scale it is important that you have a water test kit that will test for these factors and that you strive to maintain balanced water chemistry.
How do I fix it?
Step 1. Adjust your chemicals to get the correct levels of pH and alkalinity. Using a water test kit check the water every 4-6 hours and adjust as needed to get pH levels in at correct level of 7.4-7.6. Having the correct chemical levels should help the scale loosen up and begin to dissipate.
Scrub the spa surface to try and loosen the scale. If the scale is fairly new it may simply brush off but for harder, firmly deposited scale you may need to drain the spa and use a cleaner like ProTeam Surface Clean and a Pool and Spa Scrubber Brush to remove the scale build up on your surface.
We recommend you do not use household cleaners or anything that does not say it is specifically for hot tub use as these items could scratch your surface or cause water chemistry issues and foaming.
Step 2. If you had to drain the spa refill it. If you are having calcium hardness issues we recommend the use of a Spa Pre-Filter at the time of refilling your spa as it can help remove excess minerals from your water prior to it being put in the hot tub.
Once your tub is refilled, balance your chemicals making sure they are all at the recommended levels.
Step 3. Add a Stain and Scale Preventer, like Spa Pure Stain and Scale Preventer, and continue to add the recommended dosage weekly to help avoid further hot tub scale build up.
The key to maintaining a happy, healthy spa environment free of hot tub scale or other irritating water issues is to constantly maintain proper water chemistry. Test your water using a good test kit often and make adjustments when needed.