PH 8.0 - OK if CSI Good?

[matthewsunshineflorida]

TLDR: pH rises from 7.2 to 8.0 in 60 hours, but @JoyfulNoise said he is able to go 10-14 days without adding acid due to proper TA and Borates. I'm wondering if I should lower my TA a bit, increase my CYA a bit, and add borates?

Hey all, so appreciate your help both directly and indirectly through just reading through the forums. My pool really has been trouble free in terms of chemicals and I can't understate how satisfying it is to have simply never had algae, never had eye or skin discomfort - TFP has made it a very simple series of concepts that are remarkably predictable.

However, the pH is just going up way too fast for my preference. On Thursday at about 7pm, I tested pH at 8.0 and put in the suggested amount of muriatic acid to bring it to 7.2 (I know that's low, wanted to see how it would affect the rise). I tested at 7.2 two hours later at 9:30pm. Just 12 hours later, the pH rose to 7.4 (Friday at 9:30am). I did not test the water yesterday but this morning at around 9:30 the pH was 8.0 again.

I generally test my water 2 or 3 times per week and my pH is ALWAYS high so I'm ALWAYS adding around 16oz to bring it from 8 or 8.2 to 7.4 nearly twice a week because I know in 3 days it will be right back up. While this isn't an awful terrible thing, I'm hoping there's a way to slow down this process so I can adjust only once or twice a week and end up in that 7.6-7.8 range during that time.

RELEVANT POOL DETAILS:
• Filled 04/23 - plaster pebble finish
• 12,500 gallons
• 1 bubbler on a 3hp intelliflo that I keep on 600 RPM 24/7 split in half with a bypass valve so it just barely breaks the surface of the water
• 1 5ft sheer descent that I never turn on because it's messed up and is being replaced
• 1 5ft spa spillover that only trickles over the side with hardly any bubbles visible at the 1700 and 2100 RPM settings I run it at. I only run it for a few hours sometimes on the weekends

TAYLOR 2006C TODAY:
PH - 8.0
TA - 70
CYA - 50ish (I can see that stupid dot no matter what, but based on pool store testing I think I'm getting the hang of what it should look like)
FC - 12.2 (getting pump speeds and timing dialed in and accidentally bumped this up too high)
CC - 0.0
CH - 340
SALT - 3000
TEMP - 86

 

[Kenepo17]

according to pool school, CYA chart a salt generation pool needs be bet 70 & 90

The Free Chlorine and Cyanuric Acid Relationship

Managing your cyanuric acid and Free Chlorine levels is key to stabilizing your pool. Learn how these two items affect each other.

www.troublefreepool.com

 

[Rancho Cost-a-Lotta]

Have you tested the TA of your fill water?

 

[JamesW]

What is the CSI?

 

[matthewsunshineflorida]

according to pool school, CYA chart a salt generation pool needs be bet 70 & 90

Yea with all the rain we've had, my CYA has gotten washed out along with Salt and CH - have been bumping it all back up a little at a time. I've typically kept it around 60 while I try to dial in my SWG and pump runtime/speeds - haven't been brave enough to go 80 as I'm wanting to be positive I understand our SWG and will have no problem maintaining my FC level (definitely wouldn't want to have to SLAM at a CYA or 80 or 90).

So far so good so I'll raise it up 10 at a time until I end up at 70 to 80. However, if I understand it right after the video, similar to TA, CYA only buffers your pH from dropping - not rising so I'm thinking this has no effect on my pH issue.

Awesome photo of your pool by the way, you have a two story screened in area?

Have you tested the TA of your fill water?

I haven't had to fill the pool except at the beginning - we've had more than enough rain. Actually could be pretty interesting to leave a bucket out and test the rainwater but what would be the goal there? To see if the rain is basic or acidic maybe?

What is the CSI?

At a ph of 7.8, Pool Math says it's 0.02. Whereas 7.6 brings that to -0.18 and 8 brings it to +0.21. However, 7.4 does bring it to -0.37 so maybe from now on I'll only bring it down to 7.6 and just try to do it every other day or something. Thanks for the heads up, I haven't paid much attention to the drastic impact low pH has on CSI.

 

[red-beard]

Your TA reading is 70, CYA is 50. Water temp 86. You need to do a correction to carbonate alkalinity and the check the pH chart. @JamesW for help.

And check out this thread on the Ta to CA adjustment.

 

[JamesW]

Low CSI can increase pH rise from the plaster because the plaster releases calcium hydroxide.

High CSI can also be a problem as it can create scale.

Staying in the -0.2 to 0.0 range is probably ideal for newer plaster in my opinion.

Once the plaster is fully cured, -0.3 to 0.0 is fine.

 

[JamesW]

You need to do a correction to carbonate alkalinity

PoolMath does the calculation automatically.

 

[red-beard]

I have a very small spillover from my spa to pool (3" drop) but it seems to drive the pH. I have my CA down around 40. TA is ~75. The Chart for pH maximum is here and the correction from the Taylor kit below that

 

[Rancho Cost-a-Lotta]

I haven't had to fill the pool except at the beginning - we've had more than enough rain. Actually could be pretty interesting to leave a bucket out and test the rainwater but what would be the goal there? To see if the rain is basic or acidic maybe?

High TA fill water would lead to pH increase. Rainwater is more on the acidic side, so that's not the issue.

I added borates a few weeks ago to reduce calcium scaling from the SWG cell. Borates will slow pH rise, but you'll need more MA to drop pH the same amount. You won't reduce MA consumption but you'll be able to extend the amount of days between dosing. I went from every 2-3 days to 4-5 days between MA additions. From a subjective standpoint, water feel and appearance seems to have improved.

 

[matthewsunshineflorida]

Staying in the -0.2 to 0.0 range is probably ideal for newer plaster in my opinion.

Once the plaster is fully cured, -0.3 to 0.0 is fine.

I added borates a few weeks ago to reduce calcium scaling from the SWG cell. Borates will slow pH rise, but you'll need more MA to drop pH the same amount. You won't reduce MA consumption but you'll be able to extend the amount of days between dosing. I went from every 2-3 days to 4-5 days between MA additions. From a subjective standpoint, water feel and appearance seems to have improved.

That's really helpful to know. That means I really need to target that 7.6 to 7.8 pH a lot more carefully than I've been doing.

I'll raise my CYA a bit to 70, lower my FC to target 5 or 6, bump CH slightly to 370ish, let TA slowly drop to 60 naturally. I'll add 35lbs of borates to get to 55ppm. Might not add anymore next season, just really want to protect the pool by stabilizing the pH better.

 

[Kenepo17]

Yea with all the rain we've had, my CYA has gotten washed out along with Salt and CH - have been bumping it all back up a little at a time. I've typically kept it around 60 while I try to dial in my SWG and pump runtime/speeds - haven't been brave enough to go 80 as I'm wanting to be positive I understand our SWG and will have no problem maintaining my FC level (definitely wouldn't want to have to SLAM at a CYA or 80 or 90).

So far so good so I'll raise it up 10 at a time until I end up at 70 to 80. However, if I understand it right after the video, similar to TA, CYA only buffers your pH from dropping - not rising so I'm thinking this has no effect on my pH issue.

Awesome photo of your pool by the way, you have a two story screened in area?



I haven't had to fill the pool except at the beginning - we've had more than enough rain. Actually could be pretty interesting to leave a bucket out and test the rainwater but what would be the goal there? To see if the rain is basic or acidic maybe?



At a ph of 7.8, Pool Math says it's 0.02. Whereas 7.6 brings that to -0.18 and 8 brings it to +0.21. However, 7.4 does bring it to -0.37 so maybe from now on I'll only bring it down to 7.6 and just try to do it every other day or something. Thanks for the heads up, I haven't paid much attention to the drastic impact low pH has on CSI.

thanks, i have a 2 story house but cage is up to underneath my second floor windows.

 

[matthewsunshineflorida]

Actually, I do have one last question. I understand the reasoning behind an SWG pool requiring a lower minimum FC for a given CYA. However, since it's so easy to chlorinate - what's the reasoning behind choosing to lower FC to 5 instead of just keeping it 8-10?

You'd use a LITTLE more SWG generation but not that much, right? Does FC affect pool equipment, plaster, or skin in a more negative fashion at 10 vs 5?

For instance, my salt level dropped so drastically it caused my cell to turn off last week (I wasn't previously tracking salt). I could tell something was wrong by the fact that my FC was dropping from 10 to 8 then 6 (I kept adjusting SWG up without checking salt like a dummy).

Point is, I went an embarrassing amount of time with no chlorine generation and was still above the target - kind of a nice perk to being high rather than low and that wouldn't be the case if I targeted 5. Thoughts?

 

[mknauss]

Many folks here with a SWCG run at 10% of CYA as their base level. No issue in that. Try it.

 

[Rancho Cost-a-Lotta]

My CYA is at 70 with an SWG. I'm on a Time of Use energy plan Because I run at my pump and SWG primarily overnight, I use the liquid chlorine FC levels for my pool. I target an FC of 9 ppm and burn about 3 ppm during the day. This gives a bit of a buffer above the minimum of 5 ppm. If the levels are acceptable for liquid chlorine, they'll work fine for SWGs.

SWGs run during the day can target lower levels because FC is being generated as it's being consumed by the sun. Compare it to continuously pouring just enough chlorine in the pool during the day to maintain target levels. At night, FC loss is minimal so no need add chlorine.

When determining target levels, take into consideration when your SWG is on and when you're burning FC. Never allow FC to drop below minimum levels.

 

[red-beard]

I use the SWG FC/CYA chart, but I setup my SWG so that in the morning, my FC is near the top end (1.0-0.0 ppm below the top end). I run 70 CYA and a morning FC of 9-10 ppm. By the end of the day, I'm 7.5-8.5 ppm FC and will be back up to 9-10 by the next morning. I run my pump and SWG 24/7. I had Mustard Algae issues for years. No stink'n mustard for over a year! Not since TFP. And Crystal clear, if a little warm, water.

 

[matthewsunshineflorida]

TLDR: Have two concerning questions...
1) My CSI is -0.37 but modifying numbers in Pool Math, I don't see any way to get it close to 0 as even a pH of 8.0 only brings it to -0.20. If I increase CH to 450 and salt at 3600, it brings me to -0.27 with 7.6pH (-0.15 at 7.8pH). What do I do here?
2) TA is 70 even though I only ever increased this ONCE over three months ago when first balancing it, despite the insane amount of acid I put into this pool. How is that even possible?

It's BORATES DAY. Here's to hoping for the best because this is insane:

August 5th at 2pm pH was at 7.8. I added 6oz to bring it to 7.6. August 6th around 6pm it was 8.0!!! I added 12oz to bring it to 7.6 which I tested and confirmed at 9pm last night. Barely more than 12 hours later it was up to 7.8 so I added 8oz and tested to confirm it is now 7.6. This is simply RIDICULOUS.

Added 40lbs of Borates to bring the pool to 67. I read from some users who ran it slightly higher, and with my insane pH increase I'm really hoping to stabilize it a bit. I likely won't add anymore even next year unless the pH rise noticeably changes again, I figure I'll let it drift down on its own.

Test results before adding borates:
pH: 7.6
FC: 9.0
CC: 0.0
CYA: 70ish? I hate this test because I can ALWAYS see the dot in sunlight
CH: 340 -> 360 (added the last pound of the bag probably will go to about 360)
SALT: 3200 -> 3600 (added a 40lb bag to bring it to 3600)
TA: 70 (see question above)
CSI: -0.37 (pretty concerned about this)

 

[red-beard]

What is your water temp? At 90F, your CSI would be -0.26. To get -0.37, your water temp has to be 77F. I cannot believe that your water is 77F this time of year.

 

[ping]

Are you running the bubblers, sheer descent, and/or the spa spillover?

If you can add a small amount of acid each day, like half a cup the pH will be a bit more stable in the long run. Large additions make the pH swing faster due to the pH rising faster when it is lower.

 

[matthewsunshineflorida]

What is your water temp? At 90F, your CSI would be -0.26. To get -0.37, your water temp has to be 77F. I cannot believe that your water is 77F this time of year.

83 today, have had tons of rain. Normally 83-87 lately. I'm just telling you what the pool math app says, see the attachment. You think it's wrong for some reason?

Are you running the bubblers, sheer descent, and/or the spa spillover?

If you can add a small amount of acid each day, like half a cup the pH will be a bit more stable in the long run. Large additions make the pH swing faster due to the pH rising faster when it is lower.

Nope, bubbler runs 24/7 on 600 RPM split with a bypass so it doesn't even break the surface, no aeration at all. Have a spa spillover and waterfall neither of which have been on this whole time I get that rise.

Also, notice I did exactly that - I've added acid daily a little at a time to get to 7.6 and yet it went to 8.0 in no time. Look at the timeline in my last post - pretty wild!