Calcium Hardness

[ThomasG]

Just wondering if someone could explain the rationale behind the revised suggested CH levels for pools using SWGs.
Thanks.

 

[JoyfulNoise]

Easy-peasy - many plaster pool owners find that their pools drift up in pH especially those that use SWG's. There were lots of threads this season with people asking why that was the case and, when they were instructed to lower their TA to find the right level, they were a bit reticent because the TA that gave them stable pH was a bit lower then the recommended levels. Fearing a CSI that was too negative, they also asked if that was ok. The answer was to raise the CH to compensate for the lower TA and more negative CSI. So many asked why the TA was set so high and CH set low if they were allowed to go outside the range and many felt a bit of annoyance that they did not know they could go outside the levels. So, at the end of the day, the CH levels were revised (and the TA levels too) to give people more flexibility in finding a pH sweet-spot while still keeping the CSI in the proper range. If your CH levels are a bit outside the Recommended Values (heck, my CH is 750ppm and I'm all good), that's ok as long as your CSI is properly balanced.

 

[ThomasG]

Thanks. Plaster is just 6 months old, so I"m not expecting stable pH yet. CSI is always close to zero.