Adjust Calcium Hardness before Closing?

PatG25

Active member
May 19, 2010
35
Durham, CT
So it's that time of the year again; pool closing. I did a Calcium Hardness check last week, and it was 430!! I have well water that is very hard, but I am surprised it is this hard. I had to refill almost my entire pool in the beginning of the season, then I added chemicals to make it harder.

Over the hot summer I did have to put the garden hose to it quite a bit, so now it is 430. What do I do now. The pool is being closed in a couple of weeks, and water is being pumped out to be below the inlets. Do I need to do something about it now or wait until the spring. Also, how do you make water softer?

Thanks!
 

crystal clear

New member
Sep 30, 2010
2
You can't take the calcium out but you can put it in jail so to speak with a sequestering agent. Just about any pool store will carry a scale inhibitor or sequestering agent for high calcium. And I would definitely take care of it before you close it.
 

Bama Rambler

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2009
22,969
SouthWest Alabama
Since pool R/O isn't available yet in CT. Your only option to actually lower it is to replace water with low CH water.

To prevent scaling over the winter you need to get your CSI pretty low so the possibility of it climbing while closed is minimal.

Use the Pool Calc to adjust things to get it below zero.
Just for grins and giggles post a full set of test results.
pH
FC
CC
TA
CH 430
CYA
 

PaulR

LifeTime Supporter
Jan 11, 2009
1,966
Cupertino, CA
CSI will go down as temp goes down, so the risk of scaling over the winter should be on the low side. With a full set of numbers we can be more specific. Next spring you really want to run your well water through a water softener so your refill will help dilute the CH.
--paulr
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,082
San Rafael, CA USA
The saturation index doesn't go down as much as one might think because as the temperature drops, the pH rises, all else equal. This is because the equilibrium of water with hydrogen and hydroxyl ions is temperature dependent. Going from 85ºF to 55ºF would also have the pH rise from 7.5 to 7.7 so the saturation index only drops by about 0.07 units. Of course, the pH could vary more depending on what goes on with rain water, outgassing, etc.
 

PatG25

Active member
May 19, 2010
35
Durham, CT
Did a check on the pool yesterday. We got a lot of rain here in the Northeast from the storm, so I had first pump a few inches of water out of the pool. BTW, it is a salt water pool.

CL - 2 ppm (had my salt system off for a while since the chlorine was very high)
FC - 0
PH - 8 (already put muriatic acid in. Its a plaster pool only 2 years old so ph still goes up quite a bit)
TA - 90
CH - 380 (a lot lower than the last reading. Maybe the rain water lowed it; or I didn't do the previous reading correctly
CY - 50

I also checked my well water CH. It only came in at 150; much lower than I would have thought. BTW, is 150 high for well water??

I guess a CH of 380 isn't that high and should be OK for the winter?
 

Bama Rambler

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2009
22,969
SouthWest Alabama
Maybe the rainwater lowered the CH but it would have taken a lot ot lower it that much. Whatever did it, it's a good thing.

150 CH isn't bad at all for tap water.
 

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