Adjusting Calcium Hardness Level


Bronze Supporter
Nov 8, 2016
Mesa, AZ
Moved from HERE

Since my CH was at 900 and my CYA had spiked I decided to do a water exchange. Here are my readings before and after:
CYA100<30 (the black dot at the bottom of the view tube finally disappeared after passing the 30 level)0
CSI0.030.43 (I used 25 as the CYA level)0.6 (I used 100 for the salt level)

I try to follow the Pool Math table suggestions. After reading the questions and answers above, I wasn't sure if I should continue the exchange to get the CH down further. I will have to add salt. My system recommends 4000ppm. Given my fill water readings, I'm not sure if trying to stay within the pool math suggestions is realistic.

As always, any and all help is greatly appreciated.
Last edited by a moderator:

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
It may be tough to get the CH much lower since your fill water is so hard already. You can try, but don't be surprised if it just sticks at one spot and doesn't drop any further. Beyond that, adding softened water or collecting monsoon seasonal rains may be another option to add softer water. Definitely keep the pH a bit lower to prevent scale and watch it vigilantly throughout the year. You can probably lower the TA down to about 60 which should help slow the rise of pH. In the summer, use a cover to help reduce water evaporation if you can which in-turn helps to lessen the amount of hard water being added each week.


Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
If you feel you can safely drain 50% of your pool water rather then continue the water exchange you should be able to get your CH down around 450 ppm.


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
Consider a whole house water softener as a possible alternative..........or drain as ajw22 says. 450 is very manageable


Mod Squad
LifeTime Supporter
Jan 17, 2012
Evans, Georgia
When is the rainy season there in AZ? Every time you can drop an inch or two of water and refill with rain, it will help. Some folks actually aim their gutter outlets into the pool (put something on end to filter roof schmutz).

Maddie :flower:


Bronze Supporter
Nov 8, 2016
Mesa, AZ
Thanks for all the feedback. This is why I love this site. :)

Isn't a drain and refill essentially the same as an exchange?

Our rain mostly comes in July. We might get some spring rains in April.

Also regarding the CH test itself, for me when the color of the water changes, it goes from red to a shade of lavender and stays there for many drops before eventually turning blue, and even then it's a light blue, so I'm not sure I'm interpreting the results accurately.
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Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
Laughlin, NV
Your before and after exchange test results do not mesh up. Your CYA dropped by 75% and your salt fell by 50%. It seems like your exchange was at best 50% efficient. I suspect the water temperatures were close to the same or some other factor made the exchange not operate well.

This time of year, there really is no reason to do the exchange, just drain and refill with fresh water. Up to you if you want to do that now. By sometime mid to late next year the CH will be such you will need to do it again anyway.
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