Salt Pools and High Calcium Hardness

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A common issue with salt pools with high calcium hardness in the water. Photo credit - Clark County Pool & Lawn

A common issue with salt pools with high calcium hardness in the water. Photo credit – Clark County Pool & Lawn

This isn’t the first post we’ve written about the challenges with using salt systems in swimming pools where high calcium hardness is an issue. Simply put, most salt systems can’t handle calcium hardness higher than 400-600 parts per million (ppm). This means that scaling has occurred on the electrode plates and it will know longer produce chlorine for the swimming pool. It is an extremely common issue in our area and once calcium hardness gets to a certain level you will need to change out the water in your swimming pool. This is something we recommend every two years and depending on what type of salt system you have if you want it to work than it might need to be changed out every year! With that said we want everyone to understand that water coming out of the tap in the San Diego area is around 400 ppm which means even if you drain and refill your swimming pool, you might have the same issues. That’s why we recommend recycling your swimming pool water using our mobile filtration trailer which uses Reverse Osmosis (RO) filtration to lower the following issues:

  • Calcium Hardness
  • Total Dissolved Solids (TDS)
  • Cyanuric Acid (CYA)
  • Salts
  • Phosphates
  • So much more

Recently, we were called to a customer’s house because he was having issues with his salt system in his 24,000-gallon swimming pool. His TDS, salt, and calcium hardness were way too high for the system to work. His initial chemistry was:

Calcium hardness – 1140 ppm

TDS – 10640 ppm

Salt – 6912 ppm

CYA – 70 ppm

After filtering his swimming pool with RO membranes for 23 hours we were able to conserve 85% of his existing water and leave him with the following chemistry:

Calcium hardness – 150 ppm

TDS – 1139 ppm

Salt – 788 ppm

CYA – 10 ppm

Filtering your swimming pool water with Reverse Osmosis gives you drinking quality water in your swimming pool. There is no way you can get 150 ppm calcium hardness coming out of your tap which means this type of filtering is the best for all swimming pools especially salt pools. Not to mention, water conservation which is vital in Southern California! If you have questions about our service, contact us today to learn more and let us help your salt system work the way it was meant to!


  1. Rizzo says:

    Keep in mind there are products out there to help control and even lower high Calcium Hardness levels in pool water. My favorite is Scale Free by Natural Chemistry – their products are phosphate free, which in a salt pool goes a long way since ideally you want 0 phosphate level. Another product on the market is made by Earth Science Labs called Pristine Check, which I would recommend double dosing with, to any pool with very high Hardness levels. Scale free would work best on moderately high Hardness levels & is also a great maintenance product to add routinely to your pool in order to effectively combat against scaling. Keeping your salt cell free of scale is key to the longevity of your ECG (Electronic Chlorine Generator). Signed, regular pool guy

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