Any Ideas why my pH is so high when I fisrt open the pool?

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dfiletti

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Jun 12, 2008
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Thornton, PA
Folks-

Opened the 28K gallon pool yesterday, and again this year there was significant build up of lime scale on the walls and floor of the pool. It does brush off with a wire brush but there was literally many pounds of the stuff. Initial testing of my pH was off the charts so I began adding acid. It took 8.5 gallons of 31.5% acid to get it down to 7.2. Using the pool calculator in reverse, it would seem that my pH was 11.5! I know that the pH the morning the pool closed 6 months ago was 7.2.

The pool was completed construction 2 years ago. I would have thought that the 'new plaster effect' would have mellowed some but apparently not. This is fairly similar to last years opening. How much longer/ how many more openings should I anticipate this?

Any input as to what else may be causing this, or way to treat this would be greatly appreciated. Should I be testing and adding acid during the winter months, under the solid cover? Also, is my assumption that the lime scale is a result of the high pH correct?

Thanks for your input.

Dan
 
You have some issues with water quality that much is certian. This sounds like a job for chem geek or jason . I would guess it almost has to be the plaster. Just curious, why was your ph at 7.2 at closing?
 
Something most definitely does not sound right about this. 8.5 gallons of Muriatic Acid (31.45% HCl) would lower the TA by 152 ppm so it's very strange that your TA would have been over 200 ppm to begin with. If your TA started out at 200 ppm, then the pH would initially be at 11.1 to get to 7.2, somewhat similar to what you found. Again, very very strange.

I can pretty much replicate your results by assuming that the plaster was curing such that the Calcium Hardness (CH) increased by about 150 ppm as a result. Have you noticed such an increase (it might be less if you had winter rain dilution)? Of course, it is very strange to have plaster continue to cure at that rate nearly 2 years after construction.

I don't have an answer for you, though it does act as if the plaster was curing. It most certainly could not be carbon dioxide outgassing since that is self-limiting. It has to be some sort of base getting into the water.
 
Do you happen to know who made the plaster for your pool? Is thier some way the mix could have been contaminated by ???, that would cause the plaster to never cure? I know if you put sugar in cement it will never cure. Just some food for thought for you chemists out there.
 
The plaster was made by a company called Aquavations, and it's called "Hydrazzo". It's apparently an aggregate type, although it is polished and supposed to be very smooth.

I target 7.2 pH as, with the SWG, it creeps up to ~8 within a week or so, so I add acid to bring it back down.

I'll post full water chemistry later in the week, I'm out of town for a few days.

Thanks for the input guys!

Dan
 
Opened the 28K gallon pool yesterday, and again this year there was significant build up of lime scale on the walls and floor of the pool. It does brush off with a wire brush but there was literally many pounds of the stuff.
Click to expand...
I'm curious...what did it look like? I had a similar problem this year as well...pounds of salt like stuff all over the pool.
 
mamasproject said:
Opened the 28K gallon pool yesterday, and again this year there was significant build up of lime scale on the walls and floor of the pool. It does brush off with a wire brush but there was literally many pounds of the stuff.
Click to expand...
I'm curious...what did it look like? I had a similar problem this year as well...pounds of salt like stuff all over the pool.
Click to expand...


Sounds like you and I had the same thing. I am assuming it is coming from the high pH, which I am in turn assuming is coming from the plaster itself. It does look like salt. How old is your pool, was this the first year you had the issue, and there were other years that you did not have the issue?

I'd like to know, this may indicate it is somehow preventable. This I do know: next year I'll be measuring and treating the pool pH during the winter to see if I can prevent the scale.

Dan
 
As promised, here are my numbers:

Date: 5/15
Temp: 63F
FC: 0
CC: 0
TC: 0
T/A: 90
C/H: 460
CYA: 40
Salt: 2,900ppm
pH: 7.4
Filter pressure: 22 PSI
SWG Setting: 20%
Pump Run Time: 24/7
Heat Pump: Standby

Action taken after readings gathered:
Added ~100 oz. of CYA
Added 45 lbs. of Salt
Increased SWG Setting to 40%

pH seems to have stabilized, although in less than a week, I have added 10 gallons of HCL2 to get it to that point.

The Calcium Hardness seems very high. Should I be concerned about this? This seems particularly odd to me given that water was completely replaced late last summer after to PB re-polished the plaster.

Any other input sure would be helpful.

Thanks,

Dan
 
Your numbers are looking fairly good. The main thing to do is to raise CYA, which you have already started on.

Your CH level is a little high, but no big deal. You should bring the TA level down just a bit to compensate. Actually, there is no rush on that, TA will come down on it's own over time. Let the TA come down into the 60 to 70 range. In the mean time, just make sure the PH doesn't go above 7.8.

When FC gets down to zero, it is often best to add some extra chlorine manually. The SWG alone can't always raise FC up if it starts at zero.
 

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Regarding re polishing: loong story, but I paid the PB an extra $5k for the Hydrazzo, it was supposed to be smoother/ harder, more durable, longer lasting than regular plaster. All sounded good, so I bought in. The installation process looks similar to conventional plaster, but the plaster is to cure for 24 hours and then be polished to silky smoothness, before water is put in the pool.

Indeed, when they installed it, it was VERY smooth, like 1000 grit sand paper, but they left foot print and streaking marks on the surface. The plaster sub told me directly that this was due to their team not keeping the plaster wet enough while doing the initial polishing at installation time.

So, two summers ago, the year the pool was built, they did an acid start-up -dropped my pH waaay low for a ~week with brushing. and it looked great, but was etched like 60 grit sand paper. So I complained incessantly until they came back and re polished it late last summer. It's more smooth now, maybe 300 grit paper, although not as smooth as it was, and it's still really rough, 60 grit, down by the drain.

BTW: Calrton Pools is, in my opinion simply not worth dealing with. Dealing with them on this was a miserable experience for me.

There is a much longer writeup, titled "Carlton Pools Review" with all the gory details on this, in the reviews section.

Dan
 
Oh, sorry, you asked what they used to do the polishing/ re-polishing: Both times the pool was emptied of water, they used a pressurized water powered orbital sander (like a pressure washer with a sander on the end). I believe the sanding media is diamond paper.

Dan
 
I did not measure the refill water right away. My first full water test was a few days later. At that time, the CH was 140, 5 days after new water was added, from the re-polishing. This was mid-August of last year. The pool was closed mid-September.

Dan
 
dfiletti said:
mamasproject said:
Opened the 28K gallon pool yesterday, and again this year there was significant build up of lime scale on the walls and floor of the pool. It does brush off with a wire brush but there was literally many pounds of the stuff.
Click to expand...
I'm curious...what did it look like? I had a similar problem this year as well...pounds of salt like stuff all over the pool.
Click to expand...


Sounds like you and I had the same thing. I am assuming it is coming from the high pH, which I am in turn assuming is coming from the plaster itself. It does look like salt. How old is your pool, was this the first year you had the issue, and there were other years that you did not have the issue?

I'd like to know, this may indicate it is somehow preventable. This I do know: next year I'll be measuring and treating the pool pH during the winter to see if I can prevent the scale.

Dan
Click to expand...

My pool was completed last October 09. We had it closed by the PB 4 weeks later. Since they closed the pool I have no idea if they even tested the ph before they closed it. I do know that during the winter I tested the water and ph was high...off the color chart, but reading have discovered that high cl levels and cold water will give a false high reading. Upon opening this year the ph was still high...off the color charts again. I had the pb take a sample of this salt looking stuff and they had no idea what it was. Pb did say that it could be from the quartz finish. In my opinion he didn't know what he was doing. I never got a straight answer from them. All I know is that next closing I will make sure the ph is where it's supposed to be. As far as doing something over the winter about the ph...you can't. Basically your hands are tied...no pump running=no adding chemicals! And I'm still getting this stuff in my Polaris bag...just a lot less of it!
 
So, it does not sound like polishing plaster is all that familiar to folks on this list, but I'll ask anyway. Given Chem Geek's accurate prediction the the CH increased by ~150 (maybe even more), and that that behavior could be consistent with curing plaster, I wonder whether anyone has any input on my theory. It goes as follows: re-polishing the plaster, somehow caused my two year old plaster to want to "re-cure" and in doing so, add base to the water? Could disturbing the surface of plaster re-expose new plaster that needs curing??

I am just guessing, but I thought I'd throw it out there.

Is this just crazy-talk?

Thanks,

Dan
 
I don't know that re-curing is correct, though it may be, but I'd have to believe that sanding the plaster would without a doubt leave some dust on the surface even if they rinsed it after they finished. That could lead to some additional CH in the water.
 
There were 5 weeks between the time the polishing happened and the pool closed. 1 week after polishing the CH was 140, it was 150 four weeks later, when I closed it.

Seems like most of the CH rise, from 150 - 460 happened over the winter.

:scratch:

Dan
 
If the PH got too low during the winter it could have caused calcium to dissolve out of the pool surface, which would have raised the CH level.

The dust from polishing, that Bama Rambler suggested, also sounds like a possibility. It could have taken a long time for the plaster/marble dust to dissolve. If a lot of dust got into the pool that could also explain what happened.
 

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