CSI when Closing?

bostonpool

Well-known member
May 29, 2017
80
Worcester, MA
Hi folks:

Pool is closing today and I've followed the instructions in the "How To" section.

I did a final test this AM. My results are:

FC=17 (drifting down from SLAMing 2 days ago)
PH = 7.8
CH = 400
TA = 70-75
Borates = 15? (I checked in June and haven't added any)
Salt = 3000
Temp = 65 deg

I was about to add some acid to lower PH down to 7.4-7.6 per the "How To" instructions.

But when I do that it seems by CSI gets very low. Like -0.4 And then if you lower the water temp as I expect over the next few months to say 40-45 degrees I'm at -0.6, which is bad.

Is it better if I keep PH where it is at 7.8? I'd like CSI to be in the proper area before closing.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Is it better if I keep PH where it is at 7.8? I'd like CSI to be in the proper area before closing.
My initial thought was to lower it a bit. But all things considered, I would leave the pH alone. Your water is slightly under negative now at 65 degrees. When that water temp drops the CSI really goes down fast. Even if the pH climbs back up to 8.2, it's still in a well-balanced range. The only other consideration would be if you know your pool's pH to climb excessively over the winter. That change could be impacted by the type of cover you use and expose to rain, aeration, and new water. But if the pH doesn't normally shoot through the roof from Nov to Apr, I'd leave it alone. Next season when you open you can adjust from there. Happy closing. See you next season. :swim:
 

onBalance

TFP Expert
LifeTime Supporter
In The Industry
Jul 25, 2011
977
Utah
I think Texas Splash provided you with some good information to consider.
Is the plaster surface also 35 years old?