Water Line Stains and Plaster Discoloration

[phipsi1237]

I'm guessing the water line stains are from the hard water. I used an old "PoolBlok" pumice stone on the 2 tiles in the first photo with the arrow. It helped, but once it was wet, I couldn't tell whether or not it was doing any good. Once it dried, you can see it helped. Using the pumice stone on just a few of the tiles really ate up the pumice stone (not sure how old the pumice was, seemed a little brittle to me to begin with). Is this the best way to clean this, or should I use diluted acid?

My wife was concerned about the plaster discoloration as well. Any ideas what caused this? Is this signs of needing replastering? I actually think it looks pretty decent. When the pools full, you can hardly see the discoloration. Both surfaces are pretty smooth and even. The really large dark areas are just still wet from draining.

Thanks. More photos in next post.

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[phipsi1237]

Additional photos: Thanks again.

 

[duraleigh]

The water line white stains would appear to be Calcium. Posting a set of test numbers for your fill water may be revealing and if you have had high CH, pH and TA in the past that would certainly be an indicator, too.

Muriatic acid will probably clean them easier than pumice......start with a 3:1 water/acid mix and, if you don't get the white stains to start foaming, increase the acid strength until you do.

If the acid that runs down the sides of the pool ( rinse as you go to minimize this) removes the other stains as well, then you can be pretty sure that's calcium, too. If it doesn't seem to have any affect, then the stains might be organic and can be removed with chlorine.

I suggest you work on the water line tiles first and resolve that and then address the stains on the plaster.

 

[phipsi1237]

The CH was about 700, and the CYA was about 200 (using the dilution method). That was the reason for draining. The pH and TA have been high as well.

As for the fill water, I know it's hard. The only test I've done on it was for CH. It was about 270.

So those are definitely stains of some sort on the plaster? The diluted acid for cleaning the tiles won't hurt the plaster if it runs down? What about the grout?

 

[duraleigh]

So those are definitely stains of some sort on the plaster? The diluted acid for cleaning the tiles won't hurt the plaster if it runs down? What about the grout?

I can't guarantee the composition of the discoloration of the plaster but, as I said, you will probably know if it's calcium if some of the acid runs down onto it.

Minimize streaking by having the plaster wet and rinsing thoroughly as you finish a section of tile. The grout between the tile will also foam (and conceivably could have some erosion from the acid) so minimize just how much acid solution it comes in contact with. If you are uncomfortable doing this, I suggest you hire someone who has done it before.

 

[phipsi1237]

Well, since I drained the pool due to the CH and CYA, I already started refilling. I'll work on the tiles once it's filled. The plaster stains will have to wait.

Thanks for the replies.