High CH

[mjbarr99]

When I closed my pool last year these were my readings. (Since I have an automatic cover, I don't lower my water)
pH - 7.6
Cl - 6
CH - 300
TA - 100
CYA - 30

I opened the pool today and am in the process of converting to a SWG from liquid bleach. These were my readings
pH - 8.2
Cl - 5
CH - 500
TA - 100
Salt - 1600
CYA - 30
Water Temp - 58 deg
I added muriatic acid to lower my pH to 7.2 and checked my CH again and got a 500 reading. I've had the pool since 2016 and my CH has always been between 275 and 300. What would cause such an increase?

 

[mknauss]

The only way to raise CH is to add it, via chemicals or fill water, or having very aggressive water. The data you post above does NOT show very aggressive water.

Do you test your CH monthly? Do you add fill water due to evaporation? What is the CH of your fill water?

 

[mjbarr99]

The only way to raise CH is to add it, via chemicals or fill water, or having very aggressive water. The data you post above does NOT show very aggressive water.

Do you test your CH monthly? Do you add fill water due to evaporation? What is the CH of your fill water?

I test my CH every few weeks during the season. I do add fill water due to evaporation and splash out. I just checked the CH of my fill water and it's 300. I received a refill kit for my TF-100 test kit a couple of weeks ago so my chemicals are fresh.

 

[mknauss]

With that fill water CH, your pool water CH will rise over time.

 

[mjbarr99]

With that fill water CH, your pool water CH will rise over time.

But rise 200 ppm over the winter? It's been pretty steady since 2016. Something doesn't sound right.

 

[mknauss]

No, it doesn't. I would say the past steady CH is what is odd. If you have had to add fill water over time and have not done a large water exchange, your CH would have been rising over that time.