White flakes in my Hot Tub

Essentially, there are two reasons white flaking can occur in hot tub water.  The most common reason is a high calcium level in the source water and a general increase that can occur after months of our soaking and enjoyment. Calcium is a mineral that keeps us alive.  The human body needs some calcium to keep our hearts beating efficiently and our bones and teeth healthy. These are just a few of the areas where calcium is required for attaining a healthy lifestyle.  However, in hot tubs, we don’t want too high a level, or we may experience a myriad of frustrating occurrences.  We will explore how to determine the amount of calcium in our hot tub or swim spa and recommend acceptable target levels and what we can do to attain a good balance.

White flaking can be downright frustrating.  Turn the jets on to experience the pulsating water to loosen tightened muscles and wash away those aches and pains and all you see are thousands of white floating particles.  What is it?  Why am I noticing it now after months of crystal-clear water?  This could very well be the result of calcium deposits precipitating from your water.  Calcium not only affects the water clarity and enjoyment, it can also gain a foothold on all surfaces where water touches.  These deposits are what you may see when you boil water in a pan and notice the scale flakes on the bottom.  Typically, heater elements are the first place they attach to.  This makes your heater less efficient.  Next, surfaces inside the entire spa shell get that sandpaper feel.  In addition to these two problems, your filter(s) are now grabbing the flaking which means that your circulation and flow rates may be diminished until the filter(s) are cleaned.

Calcium levels are measured by testing.  Calcium levels in hot tubs should typically be in the range of 50-125 ppm (parts per million).   Swimming pools can and are recommended to be in the 150-300 (ppm) area.  It should also be noted that calcium level readings in hot tubs using salt chlorine generation, (SWG), should ideally be in a lower range of 25-100 (ppm) for best results. The amount of calcium in water determines if it is considered hard or soft.  Harder water has more calcium than softer water.  In Hot Tubs you want just the right ppm range of calcium for many reasons, three of which are less foaming, water that is not detrimental to components and water that doesn’t spurt white flakes with the jets on. If calcium levels are too high the simplest way to reduce it is to drain some or all the water. If your tap water has high calcium you might want to invest in a garden hose “screw on filter” that helps eliminate calcium. You should also try to keep the total alkalinity and pH in proper balance.  If your area water supply has higher calcium amounts you should keep a lower total alkalinity.  You may also use a chemical sequestering agent that will keep the calcium from precipitating from solution.  Raising calcium levels is easy.  You simply add the correct amount of calcium chloride based on the gallonage and the ppm target you wish to attain.  A reliable test kit can be one of the biggest assets you have for attaining crystal clear health water.  We do Not recommend using any test strips.  Invest in a good quality test kit.  It will pay you big dividends.

White water mold:  Many hot tub owners blame high calcium levels for the white floating particles they may be seeing or streaming from the jets when engaged.  Our research has discovered that the majority of the “white flake explosions” are whitewater mold.

This develops quite rapidly in hot tubs that are or have been deficient of adequate sanitizer over an extended period.  This can be from a week to a month or longer. Generally, we find that the mold forms when the hot tub sits empty for an extended time or that the owners have not been using chlorine or bromine as their main sanitizer.  Sometimes, if they have been using one of those sanitizers, they have not been adding enough.  Many hot tub owners want to use less or no chlorine or bromine.  A big mistake!  They are seeing lots of Internet malarkey that you can maintain a hot tub without using it or drastically less.  The CDC recommends that you always use an EPA Registered sanitizer and at the correct levels to maintain healthy water.

Many of our calls are with people who have tried to avoid the chlorine or bromine program.

How to tell what the white flakes are.  One of the simplest ways to determine what the composition of the flakes is to do the following test.  Capture a ½ teaspoon or less of the flakes and place them in a dish.  Add a 2 tablespoons of regular chlorine bleach, sodium hypochlorite, into the dish.  If the flakes dissolve within a minute or so they are mold.  If not, they are calcium. If they are mold, we recommend the following.  Purge your hot tub with our Ahh-some Gel. Follow the instructions on the label.  Refill, balance the water and be sure to maintain a higher ppm or chlorine or bromine for at least 3 days.  By a higher ppm we mean at least 20 ppm of chlorine or bromine.  That should help alleviate any residuals of the mold issue after the purge. Going forward, always maintain at least a 2-4 ppm of residual chlorine or bromine using a reliable test kit.  If the flakes are calcium we strongly recommend draining and refilling with fresh water as mentioned previously.

We hope that the information in this report will be helpful to you.

2 Comments. Leave new

  • Richard Rocky Silverman
    May 27, 2022 2:10 pm

    I don’t know if you cover this topic. After using Ahhsome I find a residual amount of product still in the hot tub. I back flow the jets I can and refill and run the tub on high for ten minutes. Still the gel product doesn’t seem to completely gone. I probably use too much of the gel. Is it ok too still use the tub?

    • Hi Richard. Thanks for the comment and the question. There will be a residual amount of Ahh-some that remains in the tub after the purge. It is a very small amount and usually dissipates within a couple of hours. Just run the jets on high for about 10 to 15 minutes after your refill, make sure you bump up the sanitizer level a little bit and it will all come out. You are 100% still able to use your tub.


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