Lowering calcium hardness...

doug527

Active member
Apr 15, 2019
39
Fl
Pool was open May, 2019. Finish is Stonescapes ,small pebbles. Have places that have become lighter in color where the pebbles seem to be diapering or looking smaller from what I was told is calcium build up. Water has always been about 300 to 370 on the hardness level. Water from hose is reading 100 ppm on hardness scale. It is a 20K gallon pool, salt. How do I fix the water and how do I fix the palm sized or smaller spots that are on the surface…..I can live with the pool as is but don't want it to get worse….

thanks, Doug
 

Rancho Cost-a-Lotta

Silver Supporter
Apr 10, 2018
1,030
Rancho Cucamonga, CA
Hi Doug. With a relatively low CH level, what you're seeing may not even be calcium scaling. How do you test your water? Posting a full set of test results will assist in evaluating whether the spots are related to water chemistry. In the meantime, read up on CSI (Calcium Saturation Index). Keeping your CSI between 0 and -0.3 will help to prevent scaling.

 

doug527

Active member
Apr 15, 2019
39
Fl
Hi Doug. With a relatively low CH level, what you're seeing may not even be calcium scaling. How do you test your water? Posting a full set of test results will assist in evaluating whether the spots are related to water chemistry. In the meantime, read up on CSI (Calcium Saturation Index). Keeping your CSI between 0 and -0.3 will help to prevent scaling.

Chlorine usually 5 to 7
Ph 7.6
Alk 90
Stabilizer 70
Temp at moment is 75 here in Florida.
but all these numbers change as you know weekly. But its the average. I failed to mentioned that rep from Stonescapes is the one that came to the conclusion my problem was calcium.
 

Rancho Cost-a-Lotta

Silver Supporter
Apr 10, 2018
1,030
Rancho Cucamonga, CA
Assuming a water temp of 65 degrees and salt at 1000 ppm, your CSI is in the desirable negative range and would not be prone to scaling. You can use the Pool Math app or the old Pool Math webpage to run your numbers and calculate your CSI.

How do you test your water?

How do you chlorinate your pool?

Do the stains feel rough?

Can you post some pics of the staining?
 

doug527

Active member
Apr 15, 2019
39
Fl
Salt water pool, test by a Taylor kit, 2006 I believe, one with the powder. Also use test strips and Pinch a Penny...
Stains are smoother if anything. pool is 75 deg. not 65…Summer it will be roughly 83 to 88….
 

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Rancho Cost-a-Lotta

Silver Supporter
Apr 10, 2018
1,030
Rancho Cucamonga, CA
Assuming your test results are accurate, and assuming a salt level of 750 ppm, your CSI is right on the positive side at about 0.02. Warmer water temps will increase your CSI. I've attached a screenshot from Pool Math (Web) that shows the CSI in the last row. By reducing pH to the 7.4-7.5 range, you'll get into the slightly negative range. Check out the page and play with pH and TA and you'll see how they effect your overall CSI.

It's hard to see the stains in the photos, but if those numbers are representative of your usual water chemistry, you're still within recommended ranges and not necessarily prone to calcium staining. Are you seeing any scaling around the waterline?

You didn't mention how you chlorinate your pool. Be careful when adding chemicals to the pool as most can cause some type of staining/streaking. Solids should not be allowed to dissolve at the bottom of the pool and liquids should be added slowly.

As I mentioned earlier, try to keep your CSI in the 0 to -.30 range to avoid calcium scaling. This article may help you self-diagnose the stains until more help arrives.
 

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doug527

Active member
Apr 15, 2019
39
Fl
Then what is it if it is not from CH? Everything has always looked good except the CH which is always 350 380….My tap from hose is 100 ppm on calcium hardness..
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Pic #3 is what finally showed me the difference (described as disappearing) of the stones you are referring to. The calcium scenario seems odd if the CSI has consistently been slightly negative and the areas you mention feel smooth not rough. This might call for a good Stonescapes expert. Someone like @bdavis466 might have seen this before. Brian?
 
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onBalance

TFP Expert
LifeTime Supporter
In The Industry
Jul 25, 2011
980
Utah
Sometimes the cement portion (cement is mixed with pebble aggregate) of a quartz finish in some areas of the pool will lighten over time. That is sometimes due to a difference in density or porosity of the surface. The more porous, the more light in color. The more dense, the darker the color.
Unfortunately, when new pebble pools receive an acid treatment to expose the color of the pebbles better, the acid will etch the cement excessively in some areas. It is very difficult to perform a consistent and uniform acid treatment. Those more porous areas will likely lighten in color over time. Nothing can remedy that. But keeping the water well balanced (CSI) will help prevent further etching.
 
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doug527

Active member
Apr 15, 2019
39
Fl
Thanks! This is more believable and acceptable than putting all the blame on water chemistry…Why didn't PC or Stonescapes rep tell me in the first place.