Calcium Hardness increasing

[jwrankin71]

Our gunite pool was finished last May and my CH started at 310 but slowly dropped due to a leak and constant refills. We finally got leaks fixed and CH has increased from 300 last October to 500 today. I know it can increase over time as our tap water is 200 CH but I haven't had to add much water over the winter and the CH continues to increase in between water additions.

Is there a plaster degradation mechanism that could cause this? I always keep my SI above -0.6 and it is typically above than -0.3.

I know how to handle the high CH just curious about the cause. Thanks. I'm not using any calcium-based products and I've used different reagents.

 

[JoyfulNoise]

Where do you live? Your location isn’t set.

Plaster only degrades under fairly corrosive conditions.

Do you have an auto fill?

 

[jwrankin71]

South Carolina. No autofill. I did find what appeared to be a chipped piece of plaster the last time I was vacuuming but I don't see or feel any changes in the plaster.

 

[JoyfulNoise]

Check reagents for their expiration dates. Make sure everything you are using is fresh.

Also, look at the extended calcium hardness test kit instructions and try the “fading endpoint” variation of the test. You can also try diluting the pool water sample 1:1 with distilled water (has to be distilled) and the multiply the results by 2. That should help improve accuracy.

 

[YippeeSkippy]

Are you sure about that 200ppm of Calcium?? Please perform a calcium test on tap water, as I show the water quality there to be soft (54ppm calcium).

Maddie Yea!! Golf week is here!

 

[jwrankin71]

Are you sure about that 200ppm of Calcium?? Please perform a calcium test on tap water, as I show the water quality there to be soft (54ppm calcium).

Maddie Yea!! Golf week is here!

you're right - i did that test last year but today it shows 50 ppm. this makes the problem even weirder.