What to Do About White Flakes in Your Spa Water

Though not a common problem in spas sometimes white flakes can appear in your spa water. These are likely to be either calcium scaling or white-water mold. So, your first task is to determine which you are dealing with.

Testing White Flakes in Your Spa Water

To determine if you are dealing with calcium scaling or white-water mold, collect a few of these flakes and place in two small bowls. Add some vinegar to one and bleach to the other.

  1. Vinegar is acetic acid.  If the flakes are calcium, vinegar will dissolve the calcium but have no effect on white water mold.
  2. Bleach is chlorine.  If the flakes are white water mold, bleach will kill and effectively dissolve white water mold but have no effect on calcium.

Another check is to examine the shell of your spa. If the flakes in your spa are calcium scaling, you will likely also find scaling on your spa shell. If the scaling is very mild and just beginning to form, it will likely seem like a powder on the shell and be easily wiped off with your finger. If the calcium scaling is more advanced on your spa shell, it will be very difficult to remove and feel like sandpaper.
Of course, determining which problem you have also determines the solution.

Removing Calcium Scaling

Though you can find quite a bit of other advice on the internet regarding calcium scaling, it’s really quite simple to remove.  The same vinegar you used to test for calcium scaling will also remove it in your spa – you just need more of it.

Generally, experienced hot tub technicians will carry 20 or 30% vinegar with them.  This is much more concentrated than the vinegar you buy in your grocery store but it quite commonly available at hardware and organic gardening stores because it’s also used to kill weeds.  Add 2 quarts to a gallon, depending on whether its 20% or 30% and the size of the spa and within less than 24 hours, all of the calcium scaling will be gone!  And the good news is it is gone everywhere in your spa because it’s been circulating throughout your spa’s plumbing.  Now purge your spa with Serum Total Cleanse, drain and refill.

However, plain-old store-bought vinegar will work just as well and will be a bit less expensive than using 20% – 30% vinegar.  If you are using “grocery store” vinegar, use 3 gallons in a 400-gallon spa.  Adjust up or down based on the size of your spa.  Again, within less than 24 hours the calcium scaling will be gone.  Now, purge with Serum Total Cleanse, drain, and refill your spa.

Removing White-Water Mold

Unlike removing calcium, getting rid of white-water mold can be a challenge. The stuff gets angry when you try to say Good Bye. Luckily, unlike the black mold* that is rather common on the underside of spa covers, white-water mold in your spa water is not common at all, but if you are the unlucky spa owner with it, you are in for a fight. You want to attack it, full force! Here are your instructions in order.

    1. If you have any significant health issues, please discuss using a hot tub with your physician, particularly if you have cardiovascular issues.
    2. Refill your spa and add a full dose of Serum Total Maintenance (1 oz. for every 100 gallons) and enough dichlor to raise the Free Chlorine level to 20 ppm.  Do not use your spa and let it circulate for 24 hours.
    3. After 24 hours, add another dose of Total Maintenance and enough dichlor to get the concentration back to 20 ppm.  Again, don’t use your spa and let it circulate for 24 hours.
    4. After 24 hours, purge your spa again with Total Cleanse, then drain and refill.

You are trying to kill every last bit of white-water mold because if you don’t get it all it will return with a vengeance.  Best to win the first time!

* We have two products to deal with black mold.  Regular use of Serum Total Maintenance will prevent black mold.  Serum Triple Action Spray will both remove and prevent black mold.

Not Calcium or White-Water Mold?

There are two other possible reasons for white flakes in your spa water, though the first is transitory and the second very unlikely today.

    1. Phosphates
      When you use a phosphate removal agent in your spa, these agents essentially bind with the phosphates that are dissolved in your spa water and create particulates that your filter then physically removes from your spa water.If you have a heavy load of phosphates in your spa water, you may see white “chalk” appear in your spa water which will be removed by your spa filter.  Your filter needs to be properly cleaned within 24 hours to completely remove the phosphates from your spa.If the phosphate concentration in your spa water is really high, this effect can be so bad as to make your spa water look like milk.  If you see this, your filter will be absolutely covered in white “chalk” and need to be replaced.
    2. Calcium Stearate
      Back in 2014 & 2015, a number of spa manufacturers had an unpleasant surprise when brand-new spas would have lots of white flakes floating in the spa water and could not maintain a proper sanitizer level.  It took a while, but they eventually found that the source of the problem was the PVC piping in their spas.Here is the backstory.  When you extrude PVC tubing you need a release agent to lubricate the die and prevent the molten PVC from sticking to the die.  It seems that back in 2014, a major PVC manufacturer, used by many spa manufacturers, started using an organic (soy based) release agent.  Of course, some of the release agent adheres to the PVC and it just so happened that at common hot tub temperatures of around 100°, these release agents reacted with the chlorine and bromine most commonly used as sanitizers in spas and created calcium stearate – the white flakes floating around in these spas.Fortunately, a solution was found which also happened to include the use of Serum Total Cleanse.  Once remediated, these spas never had the problem again, hence it’s quite unlikely you will find calcium stearate in your spa today.

Thanks for reading,

Tony Turbo