How High Can/Should I run my pH (SWG)

DB-Cooper

Well-known member
Jun 18, 2019
471
Austin, TX
Pool Size
30000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Here's my current readings:

FC - 5
CC - 0
pH - 7.8
TA - 60
CH - 525
CYA - 60
Salt - 3400
Temp - 76F
CSI - -0.04

My pH just always rises, I have a large surface area, lots of wind and it's only a 1 year old pool. I go up 0.1 - 0.2 pH a day. Last season I did 7.8 -> 7.6 almost daily. However, the my other readings, for my CSI, 7.8 or even higher is better. I know higher pH can impact chlorine production and have other effects, but what would your target pH be in this pool? What would you MA down to?

Thanks
 

Turbo1Ton

Gold Supporter
Dec 26, 2019
566
NE Oklahoma
Pool Size
14500
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I found that my pH liked to sit around 7.8. 1 year old pool also. When I took over care from the PB, I would drop it it 7.6 and it would come up to 7.8 so I'd drop it again and it seemed like I was doing that daily. I finally let it sit for a few days and noticed that it sat at 7.8 for 2-3 days before bumping up to 8. Then I would drop to 7.6 and let it go again and again, it would sit at 7.8 for 2-3 days. So maybe let it creep to 8.0 and see how many days it sits at 7.8.

I have the IntellipH now so I just try to keep the acid injection to where it maintains a pH of 7.8.

--Jeff
 
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DeanP66

Well-known member
Mar 26, 2014
1,229
San Jose, CA
You really can't go any lower on the TA, so I would concentrate on maybe bringing your CYA to 80. That will lower your CSI a little bit. You could also add borates to your pool. That will slow down the pH climb as well. If you were to introduce 50ppm of borates in the pool with boric acid, that would lower your CSI down to -0.30 which would be almost perfect for you and it will only slightly rise once the pool temperature gets even warmer in the heat of summer. One other benefit of borates is that it will help keep your salt cell clean from any premature calcium buildup.
 
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mas985

TFP Expert
LifeTime Supporter
May 3, 2007
14,416
Pleasanton, CA
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
I like to keep CSI between -0.3 and -0.6 to keep the SWG cell clean and scale off the pool surface. Also, I have very high TA/Ph/CH fill water so if I let it go, the CSI will go well above -0.3. If you have a similar situation with your fill water, you might consider an acid dosing system as I did because CSI will continue to rise over time.
 

DeanP66

Well-known member
Mar 26, 2014
1,229
San Jose, CA
I'm very similar to mas985 in that my fill water has high TA/pH/CH. It is 330, 7.6, and 300 respectively, my TA tends to constantly climb from the topping up of the pool after evaporation. I took care of the CH issue by running a line from my water softener to my pool refill line, but there's nothing I can do about the high TA except adjust with chemicals when it climbs.

I also added a solar blanket a couple of years ago to help with evaporation. I'm sure that's saved me quite a bit of refilling.
 

DB-Cooper

Well-known member
Jun 18, 2019
471
Austin, TX
Pool Size
30000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
I guess I was targeting as close to 0 as possible, but it sounds like more negative is ok. I find when I lower my pH the CSI starts to go quite a bit more negative. I've been trying to keep in the range of 0 - -0.300 with 0 being more the benchmark.

I've not looked into borates, what's the down side of that? I wish I was like Turbo1Ton where my pool would just stop at 7.8, but it really doesn't stop. Within 1-2 days I'll be over 8 and then over 8.1. I've never really allowed it to go above 8.2 which I think it will get at within 5 or so days. So that was some of the basis of my original question, if I maintained the pool at 8-8.1, my CSI would be positive but still in the range.

I honestly don't know what is causing my pH to rise so much. It really hasn't slowed down, and I can't attribute it to any one thing. It seems to be about the same now as it was one year ago when the plaster was new. I shut the SWG off for the winter and that didn't have a huge affect. The ONLY thing I can think of is just wind exposure, and winter and spring we do get a lot of wind, maybe as Summer comes in and wind dies down, that'll help aeration. Also, I don't run any features, etc. (my fountains run 5 minutes a day to just get water flowing).

As stated, what would the downside be to borates. I've thought about raising CYA, but knowing it's difficult to remove and the fact that I need more chlorine at the higher levels have been the reasons not to.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
14,416
Pleasanton, CA
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
Borates might not help much if you have high TA fill water and you rely on it. I tried borates once but it didn't really help my situation.

I've thought about raising CYA, but knowing it's difficult to remove and the fact that I need more chlorine at the higher levels have been the reasons not to.
Actually, that is not exactly true. You require higher FC levels with higher CYA levels, but that doesn't mean you are actually using more chlorine (i.e. higher SWG %). I did a few experiments many years ago and found that I used LESS FC (lower SWG %) with higher CYA even though the FC level needed to be higher. As it turned out, the UV extinction of the FC is not exactly linear with CYA.

 

borjis

LifeTime Supporter
Aug 19, 2014
3,441
Pacific NW
I would try TA 50 and see if it helps.
Yes some of us found the sweet spot at 50.
But that's as low as I would try.
 

DB-Cooper

Well-known member
Jun 18, 2019
471
Austin, TX
Pool Size
30000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Also, my fill water is city treated, CH is 125, TA is 70, but our pH in tap water is very high (8.8-9'ish). That said, my auto-fill is off, and I only fill via a water softener and only maybe 1-2 times per month.
 

DB-Cooper

Well-known member
Jun 18, 2019
471
Austin, TX
Pool Size
30000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Borates might not help much if you have high TA fill water and you rely on it. I tried borates once but it didn't really help my situation.


Actually, that is not exactly true. You require higher FC levels with higher CYA levels, but that doesn't mean you are actually using more chlorine (i.e. higher SWG %). I did a few experiments many years ago and found that I used LESS FC (lower SWG %) with higher CYA even though the FC level needed to be higher. As it turned out, the UV extinction of the FC is not exactly linear with CYA.


My issue was more just higher chlorine in general. Obviously with less chlroine loss with CYA, you likely need to use less chemical, but the overall higher chlorine levels. Due to some rain, I had my chlorine a bit higher over the weekend and I swear I could feel it in my eyes. It was probably around 8.
 

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mas985

TFP Expert
LifeTime Supporter
May 3, 2007
14,416
Pleasanton, CA
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
8 ppm is not very high. You can safely swim a levels more than twice that. But with a higher CYA, you also need to keep in mind that some of the chlorine is bound to the CYA so it is not active. The amount of HOCL is dependent on the FC level and the CYA level. So 6 ppm FC at 60 ppm CYA has approximately the same active chlorine as 8 ppm FC at 80 ppm CYA.
 

DB-Cooper

Well-known member
Jun 18, 2019
471
Austin, TX
Pool Size
30000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
8 ppm is not very high. You can safely swim a levels more than twice that. But with a higher CYA, you also need to keep in mind that some of the chlorine is bound to the CYA so it is not active. The amount of HOCL is dependent on the FC level and the CYA level. So 6 ppm FC at 60 ppm CYA has approximately the same active chlorine as 8 ppm FC at 80 ppm CYA.

Thanks, I had heard something similar but it wasn't explained as nicely.
 
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