Light grey plaster discoloration

[Sarah]

Split from this topic. JasonLion

I'm "almost" in the same boat as tldoige; my 30 + yr old gunite pool was re-surfaced last Nov.
The tech filled the pool about 48 hours later and covered it. When I uncovered this spring, I noticed "shadows" (looks like a light grey discoloration). I was told to do a "0 Alk treatment"; but decided to do some homework first. After reading all of the above info; I'm a little confused as to just WHAT I need to do (no, I'm not blonde)! If I'm reading correctly, I should "drain & sand" ???

 

[zea3]

We would like to see a current set of test results before we offer any suggestions of how to proceed. I can tell you I would never drain and sand a pool. My guess is that the CH levels will be high and you have calcium scale, but I won't really know until you post some test results. I am assuming be re-surfaced that the pool was re-plastered?

 

[Sarah]

Just tested it !
FC: 2
CC: 2
pH: 7.4
TA: 70
CH: 150 (Added 25 LBS Hardness Adjuster TODAY)
CYA: 50

Yes, the pool was sanded, cleaned (with an acid) and re-plastered in Nov 2011

 

[zea3]

That is different than what I expected. Have you tried brushing the pool?

 

[onBalance]

I think Tldoige's pool was grey plaster with whitish streaks. Is that the same for your pool, or do you have white pool plaster with blotchy graying? Please post a picture.
Is the discoloration on the walls or the floors? Is the plaster smooth or rough (like sandpaper) where it is discolored?

 

[Sarah]

Yes, I have brushed both the walls and the floor, several times.
The plaster is suppose to be white; and yes it has "blotchy grey" streaks.
The discoloration is on both the walls and the floor; and the plaster is very smooth.
The discoloration is all over. I will post pictures tomorrow.

 

[PoolGuyNJ]

Sorry, didn't see this. Fresh plaster MUST be cured at least 27 days, preferably longer. It is likely that an acid bath, as opposed to an acid wash, is needed. The contractor was grossly negligent by closing the pool 48 hours after filling. IMHO, he should be the one to correct this, not you.

Scott

 

[Sarah]

Thanks Scott, but the "contractor" is out of business. (Took about 40 telephone calls to find out). Any particular brand I should get ? I don't wan't to damage the pool further.

 

[onBalance]

I suggest determining what the discoloration actually is before proceeding. If it is indeed scale, then an acid bath can remove it and improve the appearance. But if the discoloration is gray mottling and streaking (due to improper plastering), then an acid bath will only age the pool prematurely, will not remove the gray discoloration, and will look worse in the long run.

The pool was filled, did cure, and we don't know (for certainty) what the water balance was or was not. Posting a couple of pictures may help a lot in learning what happened.

 

[Sarah]

Pictures:

 

[onBalance]

Thanks for the pictures. It is hard to be certain, but I think it is gray mottling. Perhaps others will feel that it is normal mottling, but it appears to me to be fairly significant, but not severe as I have seen before. If the plaster is smooth on the walls and floor, then I think that confirms that it is not calcium scaling, and not caused by improper water chemistry. Since your builder is out of business, not much can be done about it. Since the mottling isn't severe, it might even out somewhat over time (like a year or two).

I think that an acid bath is not the thing to do, and will not accomplish much of anything, as I stated above. Sanding will also not remove the discoloration, unfortunately. The discoloration goes deep into the cement matrix.
I know of a pool consultant in your area. PM me if you are interested, and you can get his opinion.