Remove scale????

crzl777

New member
Apr 17, 2007
3
Maryland
What is the best method to remove scale?? I would like to find out how to make my pool smooth again. Opened with very high PH and lots of scale. Pool used to be very smooth, almost slippery. Now it cuts our feet. I've used a pumice stone on the seat and the steps but that would take me forever to do the whole pool. Thanks for any help.

Numbers are:
PH 7.2
FC 4
TC 4
CC 0
Alk 85
CH 200
CYA 40-50
white plaster
23000 gallons
 

duraleigh

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Apr 1, 2007
32,866
Sebring, Florida
crzl777 said:
What is the best method to remove scale?? I would like to find out how to make my pool smooth again. Opened with very high PH and lots of scale. Pool used to be very smooth, almost slippery. Now it cuts our feet. I've used a pumice stone on the seat and the steps but that would take me forever to do the whole pool. Thanks for any help.

Numbers are:
PH 7.2
FC 4
TC 4
CC 0
Alk 85
CH 200
CYA 40-50
white plaster
23000 gallons
Do you know how it got there? Usually, scale is the result of VERY high pH. Did you have a prolonged period of high pH or a period where you didn't know where your pH was?

Is the scale only on the masonry surface or is it on ladders, etc. as well?

Leave all your numbers where they are for now....they're fine. Post back with some pool history if you can and we'll try to get some answers. Sounds like calcium has precipitated out of your water but that's a temporary guess.
 

crzl777

New member
Apr 17, 2007
3
Maryland
Duraleigh,

Hi. The pool is 4 years old and the plaster was smooth when I closed it last year. When I opened the PH was over 8.0. It was 7.5 when I closed it. Not sure why the PH went up.

So far I have been trying to keep the PH low and have been brushing it but I don't really see a difference. The scale is only on the plaster that was under water during the winter. The plaster that was above water level is still very smooth.

I'm considering an acid wash.

Thanks.
 

duraleigh

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Apr 1, 2007
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Sebring, Florida
Yeah, it certainly sounds like calcium has precipitated.

How the pH got so high is water under the bridge but, at least, now you know to keep an eye on it throughout the year.

How to cure it is a little out of my pay grade....I've never personally experienced the problem. I've read about aluminum and stainless brushes but I am not experienced enough to advise you. Common sense tells me you'll have to keep your pH quite low if you attempt to cure it yourself but, again, I don't have the personal experience.

Acid washing may end up being your best choice. Obviously, choose the contractor carefully.

Wish I could help more with the fix but I believe you've got the issue correctly identified.
 

CaOCl2

LifeTime Supporter
May 23, 2007
326
Montreal Canada
crzl777 said:
What is the best method to remove scale?? I would like to find out how to make my pool smooth again. Opened with very high PH and lots of scale. Pool used to be very smooth, almost slippery. Now it cuts our feet. I've used a pumice stone on the seat and the steps but that would take me forever to do the whole pool. Thanks for any help.

Numbers are:
PH 7.2
FC 4
TC 4
CC 0
Alk 85
CH 200
CYA 40-50
white plaster
23000 gallons
Strictly chemistry speaking, hydrochloric acid converts scale into calcium chloride, CaCO3 + 2HCL -> H2O + CO2 + CaCl. Now, the question is how do you go about doing that with a pH of 7.2! This is a good example of theory vs practical experience. Sorry I couldn't help more though.
 

JasonLion

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May 7, 2007
37,879
Silver Spring, MD
Several people over at the PoolForum, here, are having this problem. Acid washing and or sanding/grinding are all they have come up with so far. In all of the cases reported there a mesh cover and high opening PH were implicated as causes.
 

Lenny

LifeTime Supporter
May 25, 2007
20
JasonLion said:
Several people over at the PoolForum, here, are having this problem. ....
Yeah, and crzl777 is another one who's in the mid-atlantic area. We all had very high PH at opening and aren't sure why.

Mine is not that bad, thankfully, and I don't need to do an acid wash at this time. I bought a metal brush and am going to give that a try to see if I can soften up the plaster a bit.
 

CaOCl2

LifeTime Supporter
May 23, 2007
326
Montreal Canada
Lenny said:
Yeah, and crzl777 is another one who's in the mid-atlantic area. We all had very high PH at opening and aren't sure why.
Interesting. And all the pools I open up here in Canada usually have pH in the range 6.6 - 7.0 at opening.
 

KurtV

LifeTime Supporter
Mar 29, 2007
270
SE Louisiana
The high acid startup procedure for new plaster is, essentially, to bring the total alkalinity (TA) to zero and keep it there for a few days. That, combined with a relatively low pH (I'm thinking 6.8 to 7.0) and brushing with a stiff brush, will probably dissolve/remove most of the scale. Unfortunately, it will probably also remove some plaster. The trick will be to get a surface you can live with without eating too much plaster.
 

Lenny

LifeTime Supporter
May 25, 2007
20
CaOCl2 said:
Lenny said:
Yeah, and crzl777 is another one who's in the mid-atlantic area. We all had very high PH at opening and aren't sure why.
Interesting. And all the pools I open up here in Canada usually have pH in the range 6.6 - 7.0 at opening.
I understood why my PH was so high when I opened last year. The pool was new and the plaster didn't have time to cure. But this year I don't get it. I haven't checked the PH of rain water but I believe it's well below 7, correct? I have a mesh cover and we got a ton of rain this winter. I originally pumped about 16 inches of water out of the pool at closing (since I have a mesh cover) and then another 12 or 14 inches later after the pool completely filled up with rain water. By opening, I had to pump more water out to get to normal level.

How on Earth was my PH sky high??? I don't get it.
 

crzl777

New member
Apr 17, 2007
3
Maryland
Thanks for the information. I plan to lower my PH but try to stay between 6.8 and under 7.2. Rather than get the acid wash I plan to brush and then sand with sandpaper and/or pumice stone. The bottom is not too rough just the sides so I'm afraid the acid wash will etch the bottom. Does anyone know what grit of sandpaper works best?

Also, my pool had a solid cover, not mesh, but it did get rain water in it last year during a big storm because my lot is very level. I'm thinking the rain somehow made our PH rise.