Reviving out of service pool: FG & deck Refresh

[JoyfulNoise]

When reducing TA, it’s easiest to just use PoolMath to calculate how much acid to use to lower the TA by 10ppm. When the TA is high, taking 10ppm off will create very small differences in pH. As the TA gets closer to 80-100ppm range, dropping 10ppm will have a much more noticeable impact on pH. Just simply wait until your pH rises above 7.6, then hit the TA again. Acid addition will go quickly at first and then really slow down once you get below 100ppm TA.

 

[dianedebuda]

When reducing TA, it’s easiest to just use PoolMath to calculate how much acid to use to lower the TA by 10ppm.

I'm using web PoolMath and all it says to lower TA is

To lower TA you reduce pH to 7.0-7.2 with acid and then aerate to increase pH.

My last test a couple of days ago: TA=230

Like I've said in the last few posts, the PoolMath MA values to lower pH seem to be substantially understated in my current situation judged by the next day's pH level.

 

[JamesW]

Just use PoolMath to calculate the amount of acid needed to drop the pH from what it is to 7.2.

For example, with a volume of 24,500 gallons, a pH of 7.8 and a TA of 230, you would add 131 ounces of acid to drop the pH from 7.8 to 7.2.

131 ounces of acid should lower the TA by 21 ppm.

The new TA should be about 210.

Enter the new TA and pH into the calculator to see how much acid to use.

For example, if the new TA is 210 and the new pH is 7.6, you would add 96 ounces of acid. The pH rises over time. So, you lower it to 7.2 today, and it will be higher than 7.2 tomorrow, but the TA will not rise once it goes down.

Just round off to 1 gallon and test the levels the next day and repeat the pH drop calculation with the new TA entered.

 

[dianedebuda]

Just use PoolMath to calculate the amount of acid needed to drop the pH from what it is to 7.2.
For example, with a volume of 24,500 gallons, a pH of 7.8 and a TA of 230, you would add 131 ounces of acid to drop the pH from 7.8 to 7.2. 131 ounces of acid should lower the TA by 21 ppm. The new TA should be about 210.

I think I see now what I was doing wrong. Didn't realize that entering the TA was affecting the MA value in pH; I was just doing pH by itself. Explains my results. Think I have a chance now. Thanks.

 

[JoyfulNoise]

Scroll down to the "Effect of Chemicals" section at the bottom of the PoolMath Webpage. When you add a specific volume of muriatic acid to the pool, it will calculate the reduction in TA -



Because of the large volume of your pool, it takes roughly 1/2 gallon of MA to reduce the TA by 10ppm. As @JamesW calculated above, you can seen that at your current TA levels, it will take a gallon of MA to go from a pH of 7.6 to 7.2.

I prefer to use the reduction in TA as a guide rather than pH mainly because the PoolMath pH calculations are not accurate when you try to change pH by more than 0.2 units. The reaction of acid reducing alkalinity is exact because it's just simple chemistry & math, pH calculations are much more complex and dependent on multiple variables. Lower TA 10ppm or 20ppm at a time is just easier to calculate. The only caveat is to simply keep an eye on your pH and make sure it doesn't go below 7.0 for too long otherwise that can damage metal components.

 

[dianedebuda]

Scroll down to the "Effect of Chemicals" section at the bottom of the PoolMath Webpage.

Oh I'd read that ... just didn't realize that PoolMath had the smarts to consider it too. duh.

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Pump and SWG are under control of the IntelliCenter & both are working just fine.

pH=7.6 and TA=200, so heading in the right direction.

CYA=50 or maybe 60, down from the spike of 80 yesterday. Really more what I'd expected, but will wait until tomorrow to add CYA to confirm level (assuming my reagent refill arrives today).

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Next on the todo list:
pavers in pool pad to make access to the filter easier
bonding wire
cleaning the leaf & dirt mess on the deck where the solar cover is to be kept
power wash the deck

 

[mguzzy]

I'd originally planned to go for 7.0, but having trouble getting lower. Like one day I'd put in the PoolMath recommended amount of MA to go down .5 ... and the next day the pH was UP by .1 .

How long did you run your waterfall before you noted a pH/TA difference?

James and Joy jumped in and said exactly what I was going to say!... sounds like you got the TA adjustment figured out. ya know, I never actually measured how long I ran the WF... I also can run the bubbler jets in the spa and crank up the spill over, plus whatever the SWG is doing, so I kinda have a lot of aeration options. I more just monitored my pH and when I saw it got up to the high 7's I would drop it again and start the processes over.

 

[MyAZPool]

Thanks, @MyAZPool. I'd read that link when you first posted it, but had forgotten it. And you'd walked me though the same routine when I set up my relays & actuators.

Think my biggest hang up with the Pentair way is remembering that Feature Circuits are nothing but labels and that the configuration is done by going to the device, adding a reference to the label and then doing the configuration there. Sure seems bass ackwards. IMHO, just stating that would make what you're doing in the video much clearer.

Wasn't there also some oddity about scheduling for 24/7? I've read so many articles over the last 6 or 7 months...

Many, many thanks for all of the time you've spent trailblazing and documenting the IntelliCenter.

Diane, the only "oddity" (personally, I would use another term ), regarding schedules that I am aware of, is the fact that some existing schedules won't expand once they have been created (this applies to the webClient and mobile app only). I have had issues with this and other users have reported the same. Still other users have never experienced this issue. Pentair promised to fix it (as they did admit knowledge of this bug) but in typical fashion, no fix has come. Sometimes a certain schedule will expand (to allow for editing), other times it won't. It's "gremlins". One of the just several reasons why I don't use the webClient any longer.
Thanks much...
r.

 

[dianedebuda]

@MyAZPool, I didn't use a schedule, just added the pump to the Pool & Spa Ids yesterday with the expectation that turning on "Pool" would just stay on until I turned it off. When I went out today, pool equipment wasn't running; "Pool" was off. No problem turning it back on again though. Any reason you can think of?

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Had to turn down the SWG from 50% to 20%. FC=5 before I started the SWG yesterday; FC=14 today. The gallon of MA did get me down to pH=7.2 today.

 

[MyAZPool]

@MyAZPool, I didn't use a schedule, just added the pump to the Pool & Spa Ids yesterday with the expectation that turning on "Pool" would just stay on until I turned it off. When I went out today, pool equipment wasn't running; "Pool" was off. No problem turning it back on again though. Any reason you can think of?

If you want to run continuously, ensure the "Don't Stop" boxes are checked on all of the applicable AUX and FEATURE CIRCUITS. This includes the POOL AUX CIRCUIT. The Egg Timers on all circuits are defaulted for 12 hours. That can be changed or you can just check the "Don't Stop" box and whichever circuit you check will run continuously (24x7) until such time as you change it.
r.

 

[dianedebuda]

CYA still at 50 today so added 1 gal liquid stabilizer. This time using the other "old stock" jug, I poured out what I could into a bucket then sliced open the jug and dug out the rest - adding water as needed. Consistancy of peanut butter to almost dried out. No wonder I had so much trouble with the first gallon. With double/triple liquid, it mixed pretty well & I didn't have to decide on dance style.

TA=180; will have to pick up MA tomorrow 'cause I'm out.

 

[JamesW]

Each gallon of acid will lower the TA by about 20 ppm. To get down to 60 ppm, you're going to need about 6 more gallons.

Where is the pH now?

 

[dianedebuda]

pH is 7.3. Was planning to add 1/2 gal MA (target pH=7.1 for PoolMath) and take it slow.

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Most of the solar blankets want a max FC=3 which is TFP min for SWG. Is that what is usually used instead of the TFP target of 5?

 

[JamesW]

Note that liquid stabilizer will raise the TA a little bit.

Normal cyanuric acid won't change the TA because it's a weak acid.

When you add it to water, some of the hydrogen ions dissociate and lower the pH.

C₃H₃N₃O₃ --> C₃H₂N₃O₃^- + H⁺

Cyanuric acid --> cyanurate + hydrogen ion.

The cyanurate counts toward the TA and the hydrogen ion subtracts from the TA by the same amount.

The amount that becomes cyanurate depends on the pH.

1÷(1+10^(6.88 – pH)) = % cyanurate.

pH........% cyanurate
7.2............68
7.4............77
7.6............84
7.8............89

Liquid stabilizer is sodium cyanurate. At a pH of 7.8, 11 percent will become cyanuric acid.

100NaC₃H₂N₃O₃ + 11H₂O --> 89C₃H₂N₃O₃^- + 11C₃H₃N₃O₃ +11OH^- + 100Na⁺

The hydroxide ion raises the pH and TA some. The cyanuric acid doesn't count towards the TA, but the remaining cyanurate does contribute to the TA.

When adding liquid stabilizer, every 2.58 ppm of CYA results in an increase of 1 ppm TA.

For example, to go from 50 to 65 ppm CYA using liquid stabilizer, the TA will increase by 5.8.

(65 - 50) ÷ 2.58 = 5.8 ppm.

 

[dianedebuda]

OK. I'll test pH & TA again before adding MA tomorrow.

 

[dianedebuda]

FC=7
pH=7.5
TA=180
CH=350
CYA=70
salt=4050 (IntelliCenter reading; usually 200-300 higher than strips)
added 3/4 gal MA

Sure wish that FC would come down soon; SWG is off. Going to have a few days of warm weather, so it'd probably be my last chance at getting the pool light installed this season. It's a pain to have to babysit the robot, but with the light on the deck, the loose cord into the niche is vulnerable. I'm not game to brave the water at 69°, but if I can toss the solar cover on for a few days, just maybe...

 

[PieterS]

Looks to me like you have a functioning pool - nice job! This has been a fun follow this summer. Sure hope that temp can creep up a few degrees so you can 'enjoy' your pool and get that light installed.

 

[mguzzy]

I think you should green checks on all your numbers... the TA will start to align itself with your pH.. Depending on what I got going on, a FC of 7 is not too bad, I like running a dash high as a weird weather buffer. And a pH of 7.5 is purrfect. I think it looks awesome!

 

[dianedebuda]

a FC of 7 is not too bad

Apparently it is not good for solar covers - they want max of 3.

 

[Mike1162]

I wouldn't hesitate to put on a solar cover with CYA level at 70 & FC of 7.