White Flakes in Your Pool

What It’s Not

If only because we hear the question as frequently as we do, you should know that any white flakes you’re seeing in your pool or perhaps coming out the jets is categorically not salt. Importantly, these flakes are not harmful either, although they are an indicator that you may need to take action on their cause.

Fun Fact: At room temperature, salt reaches saturation in water—the point at which no further salt will dissolve—somewhere around 260,000 ppm, contrasting sharply with the typical 3,000–4,000 ppm of a saltwater pool.

What It Is

These flakes will almost certainly be calcium carbonate, just like the predominant buildup that occurs on your salt cell. In fact, the flakes will have formed on the electrodes as chlorine was produced but they sloughed off, particularly when the salt chlorinator reverses polarity. If you’re curious, collect some of the flakes and add a drop of muriatic acid. Calcium carbonate should fizz and dissolve in the acid.

Why It Is

Routine water tests measure the Calcium Hardness of your water, and it is that same calcium that deposits on your salt cell. With the localized high pH at the cell blades when electrolysis produces chlorine, that high pH interacts with the water’s calcium creating calcium carbonate. While some of this loosens from waterflow, much more will break free as the salt chlorinator reverses polarity (and the electrical current reverses direction).

Contributory factors include high readings for Calcium Hardness, pH, Total Alkalinity, water temperatures, output settings on the chlorinator, and the Saturation Index.

The Saturation Index, also referred to as the Langelier Saturation Index (LSI) or as the Calcium Saturation Index (CSI), is associated with typically high Calcium Hardness, pH, Total Alkalinity, water temperature, and chlorine output settings.

What You Need To Do

Your pH and Total Alkalinity can be lowered with Muriatic Acid. Calcium Hardness can really only be brought down by draining some water and topping up with water that has a lower Calcium Hardness—this can be a problem in some parts of the country. For most pool owners, there’s little to be done about water temperature, but the SCG can be set at a lower output level and run for a longer period of time, which will help with the flakes and also contributes to extending cell life.

Indirect help can be obtained from assuring that your Stabilizer/Cyanuric Acid (CYA) level is between 30 and 50 ppm, since some chlorine is lost to the sunlight below 30 and the chlorine’s efficacy is reduced above 50 ppm. The point in optimizing your CYA is to lower demand from your SCG. Similarly, check that your Combined Chlorine is below 0.5 ppm so that your Free Chlorine isn’t trying to oxidize the Combined Chlorine and unnecessarily requiring the SCG to be operated at a higher output setting.

Aside from changing the output setting and runtime for the SCG, these other changes all serve to lower the Saturation Index. So, an LSI calculator is the perfect tool for bringing the water back into balance. By adjusting the inputs and seeing the calculated change in the index, you can determine what changes will bring the water back into balance and reduce or eliminate the white flakes.

If we haven’t adequately explained and solved your issue, then we advise you to call us at (866) 766-5243 Mon-Thu: 9-4:30 or Fri: 9-3PM Central and a member of our support team will assist you further. Alternatively, you can request assistance online and you will be contacted by a support team member.