Winter High PH vs Low CSI

Cluckr7

Well-known member
Jun 19, 2020
89
Texas
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
Looking for thoughts on if I need to keep PH below 8 as long as CSI is fine?

My water tests:
- TA 80
- CH 350
- CYA 60
- Salt: 3200
- Typical temp: 50-60 in winter
- No borates

At a PH of 8.0, the CSI is -0.06.
At a PH of 7.8, the CSI is -0.26.

My PH tends to gradually rise (3 month old plaster, high TA fill water, SWG).

How high can I let PH get above 8.0 as long as CSI is <0.3? How low should I go below a -0.3 CSI when I add acid?

Staying above -0.3 CSI and under 8.0 Ph is a pretty narrow band...lots of tiny, regular acid adds.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,315
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
As water temperature rises, your CSI will rise.
Right now, when your pH reaches 8, lower it to 7.8. When the water warms, you will be able to go down to 7.6
 

Cluckr7

Well-known member
Jun 19, 2020
89
Texas
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
So I could get calcium scale with a PH above 8 even with a CSI of say 0.1 or 0.2?

Besides scale, are there other risks of say 8.1-8.3 PH?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,315
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
So I could get calcium scale with a PH above 8 even with a CSI of say 0.1 or 0.2?
Not likely. But you cannot measure a pH greater than 8 or so.

There are no risks from a higher pH (within reason) other than scale.
 

Cluckr7

Well-known member
Jun 19, 2020
89
Texas
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
Ok great, thank you!

I probably won’t correct my Ph until it gets to 8.2 (0.2 CSI) and see how that goes. And then dose acid so PH goes down to 7.8 (-0.2 CSI). Crossing my fingers for no scale!
 
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