Calcium Hardness

[Walter2050]

Had a huge storm yesterday. Calcium hardness was at 380 ppm before storm . Today it is at 270 ppm. Is it normal for the calcium hardness to drop after large rainstorm? I can’t recall it ever dropping before when we had extreme rain. Should I add calcium hardness or will it rise on its own?

 

[mknauss]

Rain has no hardness. So you overflowed the pool by 25%? Seems a bit much, but possible.

No need to add any calcium. Your fill water likely has CH? Do you know how much?

 

[Walter2050]

Rain has no hardness. So you overflowed the pool by 25%? Seems a bit much, but possible.

No need to add any calcium. Your fill water likely has CH? Do you know how much?

No sir I don’t know . I have tested Alkalinity and it’s high but never tested Calcium. I will test in a bit and circle back

 

[Walter2050]

Rain has no hardness. So you overflowed the pool by 25%? Seems a bit much, but possible.

No need to add any calcium. Your fill water likely has CH? Do you know how much?

Fill water is 160 ppm calcium hardness. It was a terrible downpour . I lost about 650 ppm of salt as well . What amazes me is I only lost about 10 ppm of cya . It went from 80 to 70 . I figured I would have lost a lot more of that

 

[newdude]

What amazes me is I only lost about 10 ppm of cya . It went from 80 to 70 . I figured I would have lost a lot more of that

They will all lower accordingly as an even %. 2 inches of rain in a 60 inch average depth pool is a 1/30th dilution, etc etc. But the CYA test is subjective **cough cough sketchy at best cough cough** and a 14 loss may look like 10 or 20. Or even no loss because the googley eye befalls us all.

The 1 drop test error variance can skew the results too. With the 10ml CH test, a 300 could test 275 or 325 back to back, so 50 might be normal from yesterday to today. For salt it's +/- 200. Then human error comes into play between sample and drop size and it might be off further, with no rain.

Otherwise, the math is the math. If you truly went from 380 CH to 270, you were diluted 29%. A 6 inch whopper of a storm would only be 10% for most people.

 

[Walter2050]

They will all lower accordingly as an even %. 2 inches of rain in a 60 inch average depth pool is a 1/30th dilution, etc etc. But the CYA test is subjective **cough cough sketchy at best cough cough** and a 14 loss may look like 10 or 20. Or even no loss because the googley eye befalls us all.

The 1 drop test error variance can skew the results too. With the 10ml CH test, a 300 could test 275 or 325 back to back, so 50 might be normal from yesterday to today. For salt it's +/- 200. Then human error comes into play between sample and drop size and it might be off further, with no rain.

Otherwise, the math is the math. If you truly went from 380 CH to 270, you were diluted 29%. A 6 inch whopper of a storm would only be 10% for most people.

I did the 25ml test for the calcium. Should I perform the 10ml test for a more accurate reading?

 

[newdude]

I did the 25ml test for the calcium. Should I perform the 10ml test for a more accurate reading?

Either is fine for what we need to do. Do the one that uses less reagents with 25 ppm per drop. (I'm a vinyl guy and don't usually test CH so I never remember. ) We need a ballpark figure and some variance is irrelevant. We need to know it's about 400 and not a 50 or 1000.

The point above was just to say that with a little test error, some human error and some rain, it might appear more off than it is. For example, the 29% drop you saw.

 

[mknauss]

Use 10 ml test sample to test CH. No need for more accuracy. Each drop of R0012 to blue is 25 ppm CH.