When is CSI too high? When is it time to refill???

[CavVet]

OK you chemistry experts...
FC: 7.5
pH: 7.7
TA: 70
CH: 600
CYA: 50 (slowly going to 70)
water temp: 84
CSI: 0.12

City Water:
TA: 130-150 (depending on lake levels)
CH: 150-180

• I understand that TFP promotes a slightly negative CSI with a SWG.
• I also understand that with a SWG, pH tends to drift up.
• With evaporation, i am gaining roughly 40-50ppm CH and gaining 20-40ppm TA monthly.
• I am (currently) adding 5 cups of MA to lower pH and TA about once every 4-6 days.
• With my current rate of CH gain, and constant lowering of TA, it would require me to keep my pH at 7.5 or lower to keep in the 'slightly negative' range.

However:

• As the pool cools in the fall, the CSI grows increasingly negative, so (typically) i allow the pH to drift up a bit more.
• If i refill now, and i plug in the lower CH numbers (400), and the lower water temp (60), the winter CSI tends to get very aggressive.
• If i do not refill now, i am feeding MA very often to try and keep the CSI (at least fairly) close to 0.0

Questions:

1. Would you refill now and adjust pH and TA for the winter to keep it more neutral?
2. Would you wait to refill until spring before i get more CH creep and ride out the winter with current levels? i.e., less chance of aggressive water with higher CH levels.

thanks for any guidance!

 

[Texas Splash]

Sounds like our water conditions are almost identical. I typically ride-out the summer conditions and manage my CSI with acid. When the rains return, I look forward to healthy (free) water exchanges courtesy of Mother Nature.

 

[CavVet]

Good morning!
This part of Tx is in a very long drought. My CH is now at 625 (we did have an inch of rain, and had a slight improvement).
I am curious if lowering my TA to 50 (or lower) is detrimental in some way? This, in order to keep the CSI in a reasonable range.
How do folks manage CSI with CH over 900? Do you keep your TA below 60 and pH below 7.5? seems like alot of MA additions to manage in this way.
Am I thinking correctly?

 

[triptyx]

You can safely lower TA to 50, but I wouldn't go much lower as it can cause pH instability. In AZ we fight calcium buildup tooth and nail as well. Your thinking is correct, though, TA to 50 or 60, keep pH low. As the water cools down for the fall/winter you'll be able to let your pH rise up to 7.8 or so since the colder water doesn't scale as easily, but you'll be right back into the fight in the Spring.

Your main issue here as the CH rises will be scaling on your salt cell and on your pool edges.

 

[CavVet]

I really wish there was a definitive CSI value that creates scaling. I know to keep it under the stated .3 CSI, but it would be nice to know if scaling starts at .3 or does it truly start earlier.... possibly .2? .1? Or could it be higher at .4 or greater?
I’m mainly referring to the scaling on the pool tile not the SWG cell. Cleaning out the cell = minutes, while scrubbing the tile around my whole pool = hours.
Any chemistry thoughts?

 

[Richard320]

I really wish there was a definitive CSI value that creates scaling. I know to keep it under the stated .3 CSI, but it would be nice to know if scaling starts at .3 or does it truly start earlier.... possibly .2? .1? Or could it be higher at .4 or greater?
I’m mainly referring to the scaling on the pool tile not the SWG cell. Cleaning out the cell = minutes, while scrubbing the tile around my whole pool = hours.
Any chemistry thoughts?

In my experience, 0.3 is the cut point. Scale doesn't just miraculously appear all over then, but places with lousy circulation that are hard to brush, like the inside corners where steps meet sidewall and so on. Keeping CSI in the negatives will loosen scale, but over a period of years. Again, my experience. And it doesn't lift it uniformly, either. It's blotchy.