Importance of CSI balance in winter..

[Bvacchiano]

What is the likelihood of developing scale in the winter versus the summer? I ask because for a SWG if you keep the TA at the higher recommended range of 80 it’s still pretty difficult due to water temp to keep the CSI from -.3 to 0. I play around with this all the time. In my pool in the winter with water temp between 55-62 F , TA 80, PH 7.6, CH 400, and salt of 3800 I’m BARELY outside of the recommended range. I realize this CSI range is just a guide.

In in the summer it’s much easier to keep in that range due to higher water temps.

Shoujd i teally worry about scale scale in the winter months???

 

[Texas Splash]

Should I really worry about scale in the winter months???

I think maybe you have it backwards - potential to be corrosive? I plugged your numbers into PoolMath and your CSI is about -0.32 (negative - potential to be corrosive). When the water warms up in the summer your CSI isn't so low. In your case right now, you could actually let the pH hover about 7.7-7.8 and that will keep the water from being so corrosive. Even at -0.32, it's not that bad and would take quite a while to cause any potential damage. But remember that once the water warms up in the spring, knock the pH back down to about 7.5-7.6 to avoid scale (positive end of the CSI scale).

 

[Bvacchiano]

Positive CSI for a SWG plaster pool?? Has TFP established there “Final” guideline for nominal CSI for this? I searched this site and found MANY different opinions. Most say keep at -.3 as optimum number. I haven’t found any that say keep positive.

 

[JamesW]

Just let your pH drift up to 7.8 and you're good.

 

[Texas Splash]

Positive CSI for a SWG plaster pool?? Has TFP established there “Final” guideline for nominal CSI for this? I searched this site and found MANY different opinions. Most say keep at -.3 as optimum number. I haven’t found any that say keep positive.

Exactly, keep it slightly negative (-0.3 to zero). According to your numbers above, your CSI is currently outside (below) the recommended negative range (potential to become corrosive). That's why we noted your pH should be on the higher end of the scale while the water is cold. We almost always try to avoid a positive CSI to avoid scale issues with either the shell and/or SWG plates.