Sanity Checks on Plaster SWG pH Rise in 2nd Year Pool

DB-Cooper

Well-known member
Jun 18, 2019
459
Austin, TX
Pool Size
30000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Update, I've got TA in check. It's been 60 for the last several weeks. I have not used fill water as we've had tons of rain. I've even had to pump water out (probably upwards of 9-12") and rain has refilled. That's brought my CH down a bit. Rain has slowed some of the acid creep and I recently added 4 pounds of CYA, but now that everything is stabilized, here are my readings:

FC - 6
CC - 0
pH - 7.8
TA - 60 (added CYA earlier this week)
CH - 525
CYA - 60 (may add a bit more to get to 70)
Salt - 3600
Water Temp - 80
CSI - 0.02

I'd love to get the CSI negative a bit, which I can easily do by adding acid. I'm still adding roughly 8-12 ounces per day and going 7.85 -> 7.6. Depending on weather, sometimes I get two days.

As I added 4# of dry CYA, I think my TA is probably closer to 50 as I've not been using fill water due to the rain. The weather has caused some windy days and I think rain (despite being acidic) causes some aeration as well.

So I guess my question is, should I change to swinging 7.2 -> 7.8 to buy me more time? I also have a week long trip in July and may need a friend to come once or twice to put some acid in. For reference, 7.2 would bring my CSI to -0.530, 7.0 would be at -0.710. 7.4 would be -0.350 and 7.6 would be -0.170 (this is typically where I adjust down to now).

What would you guys do? I'd love to not have to add acid more than once a week. As we're swimming daily, I also don't want to lower the pH too much to where it would affect swimmers. I add acid in the morning, and swim time is always in the afternoon, so I have good control on that. Anyways, let me know what you guys would do with this setup?

PS - Paging @mknauss since you were so helpful earlier on :)
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
39,446
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I would not push the pH down to 7.2. That will consume TA and will bounce back to a higher pH regardless.

I would not stress over the CSI unless your SWCG is shedding a lot of scale flakes, which I doubt it is with the lower TA.
 

DB-Cooper

Well-known member
Jun 18, 2019
459
Austin, TX
Pool Size
30000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
I would not push the pH down to 7.2. That will consume TA and will bounce back to a higher pH regardless.

I would not stress over the CSI unless your SWCG is shedding a lot of scale flakes, which I doubt it is with the lower TA.

Thanks, yeah no issues with the SWCG, in fact it had a major fault and Pentair just replaced it. When I looked at the plates of the old one, they looked brand new. I don't have any real scaling. I did a little last year (on tile there were some white marks) as I really didn't have a handle on chemicals and had a pool service that came with the pool builder that wasn't really good so I basically turned him into a chemical delivery service.

What pH and CSI would be considered too high? I know acid is required to basically keep NaCl going. Just wondering what's too high for when I travel. Pool math says 0.6 to -0.6 is the ideal range, that's pretty wide with a lot of buffer. I could effectively go to 8.4 pH and be at 0.600 with other readings as is. I've never really had it over 8.2 to 8.25 (winter I went away and it went 4-5 days).

Again, the goal is also to not have to do anything daily, I'd love to somehow get this thing to weekly acid pours, hence the 7.2 suggestion.
 
Last edited:

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
39,446
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Keep your CSI under 0.3 for sure. What do you mean by "I know acid is required to basically keep NaCl going."?
Have you limited the aeration created by water features, etc?
 

DB-Cooper

Well-known member
Jun 18, 2019
459
Austin, TX
Pool Size
30000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Keep your CSI under 0.3 for sure. What do you mean by "I know acid is required to basically keep NaCl going."?
Have you limited the aeration created by water features, etc?
Basically there’s no free lunch. Making chlorine from NaCl works by electrolysis and separating the Chloride from the sodium. Hydrogen is also produced as it’s a hypochloric reaction.

The acid rebinds chloride to the sodium. It’s a hydrochloric process. So I believe at some point if the pH is at some point there could be issues. I’m not a chemist, but I read a cool article years back on this.
 

DB-Cooper

Well-known member
Jun 18, 2019
459
Austin, TX
Pool Size
30000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
39,446
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
The SWCG does not appreciably effect your pH. Other factors, primarily fill water and aeration (from wind, pool use, water features) far exceed any effect of the SWCG. Many members with benign fill water never have to adjust their pH, with a SWCG.
 

DB-Cooper

Well-known member
Jun 18, 2019
459
Austin, TX
Pool Size
30000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
I haven’t used fill water in almost two months. My water fountains run just 10 minutes a day to circulate the water. I have a spa spillover but the water doesn’t crash and creates no splash, it’s almost invisible.

I do get a bit of wind but even on non-windy days I do have pH creep.
 

DB-Cooper

Well-known member
Jun 18, 2019
459
Austin, TX
Pool Size
30000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Here's a video of my spillover that runs while the pump runs (dedicated pool return into spa), constantly circulating water through the spa. I can alternatively disable this return and use automation to run this more aggressively once a day for ~30 minutes at higher pump speeds.

As water isn't crashing down, I can't imagine this is a HUGE source of pH increase. Similarly, I have bubblers on my shelf, but it's almost not able to see visually that they're running on my low pump speed mode I run.

Here's the video:
 

Enjoying this content?

Support TFP with a donation.

Give Support

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
39,446
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Easiest thing to do is to set up a Spillway function and only run the spillover for 15-30 minutes once or twice a day and see if that effects things.
 

DB-Cooper

Well-known member
Jun 18, 2019
459
Austin, TX
Pool Size
30000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Easiest thing to do is to set up a Spillway function and only run the spillover for 15-30 minutes once or twice a day and see if that effects things.
I did the last season and it didn’t seem to help. I can try again.