Recognize these pool stains?

[athan01]

My pool (ceramic tiles) has developed these stains in the material between the tiles (not sure what this is called).

Observing it from close it resembles sand. Initially i thought that the plaster was coming off, but then i realized that it is actually a deposit on top of the white plaster between the tiles. I have taken some shots with my trusty old digital camera (12 yrs old) for which I have an underwater case and I am attaching them in this post. I only got my Taylor K-2006 today so I did not get the chance to run a full set of tests yet. Will do that asap.


Any ideas what this might? I suspect metal/mineral deposits.

Assuming these are indeed some type of mineral deposits, any idea how I can get them out (without emptying the pool?) I tried to scratch them off underwater using a knife, but they are really tough and i ended up scratching the nearby tile, so i gave up.

 

[Jeetyet]

Hmmm. Are you certain that the gray is on top of the white? I know pictures can be deceiving but it sure looks like its the other way round. It seems unusual to me that something would be making deposits that are so "colorful". You'd think if something was causing a stain or deposit the color would be more monochromatic. Having said that, I don't know much about deposits on tile/grout, in pools or otherwise.

If I was making a wild off-the-wall totally uneducated guess based on what I see in the pics I'd posit that the white was either some kind of scale on top of the actual multi-colored grout, or, the grout between the tiles was applied in some two-stage process with the white being the top layer. ???

Will be interesting to see what the final result is on this. I'm sure someone here will be able to properly advise you soon.

 

[athan01]

Yes, it is certain that the colorful (as very correctly described) residue, comes on top of the white stuff.

The pool (which is 2 yrs old) was built with the white stuff and the first year a small spot of the dark stuff appeared. This year when I decided to do the pool maintenance myself, more spots appeared.

Initially i thought that the white stuff came off and i would see the concrete behind the tiles.. but that was not the case.

This residue sits on top of the white stuff.. you can touch it and feel it that it is raised...

 

[PJ]

It looks to me to be grout showing through a sealant.

 

[Bama Rambler]

My guess is that it's calcium scaling. Can you post a full set of test results and how you got them?
What happens if you pour a little diluted muriatic acid on a spot?

 

[onBalance]

I am guessing here too, but I wonder if you reside in an area that has sand that can blow in to your pool?
To me, it looks like sand is adhering to your more "porous" grout.

 

[I Know Nothing]

I'm with PJ. Sanded grout with a sealer. I did a quick check on the web and sanded grout is recommended with tile spacing wider than 1/4 inch on IG pools.

It looks to me to be grout showing through a sealant.

 

[athan01]

Thanks a lot for your feedback. I have narrowed down two possible explanations based on your responses:
1. Calcium buildup (see test results below)
2. grout showing through a sealant.

I have just finished testing my water with the K-2006 kit which i just got. So this is the first time I got to check some of the values for my pool:

FC= 6 ppm
CC=0.6 ppm
pH = 7.4
TA = 60
CH = 425
Cyanuric Acid: less than 30

I will check with the company that made the pool on the possibility that the sealant is coming off and/or the grout is pushing out.

 

[Jeetyet]

So, is it standard practice to use "grout" of one color and a "sealant" of another? And if that is indeed what we're looking at in this case, what would cause the sealant to disintegrate? Something wrong with the pH or calcium balance???

 

[athan01]

So, is it standard practice to use "grout" of one color and a "sealant" of another? And if that is indeed what we're looking at in this case, what would cause the sealant to disintegrate? Something wrong with the pH or calcium balance???

I honestly don't know if this is how it was done. It just sounded very reasonable when it was mentioned in the forum so I thought its at least plausible and worth investigating further. Even though I was around my house when it was built, there were so many things to notice (and fight with the contractors) that I can't say with confidence that I observed this specific detail on how the pool was done.

I will speak to the pool company today and get back to the forum with some details. This threat could be totally wrong if there is only sealant and no other cement/sand base grout. In that case, its back to the other explanation or to square one.

 

[Jeetyet]

Sorry athan01, I should've clarified that my questions were aimed towards some of the previous responders. I was hoping for some further input/clarification for the both of us from those who seemed to have some experience with this issue. Hope you get it sorted soon. Will keep an eye on this thread just to satisfy my piqued curiosity.

 

[athan01]

I've talked to the pool company. Their response was that they only use a sealant for the gaps between the tiles. They use a special glue to glue the tiles on the concrete wall and the glue is white, so that in case it pushes out when they glue the tiles, it will have the same color as the sealant they use afterwards.

So, that leaves the calcium builtup as the only plausible answer.. but this does not look like the typica calcium buildup I would expect, which would be white coloured and have a smoother/flaky texture...

 

[Jeetyet]

Could you send them the pics you've posted here and see what they say???

 

[athan01]

Could you send them the pics you've posted here and see what they say???

I did , right after i spoke with them. I doubt if I will get a quick answer, as the guy i spoke with is in sales and the maintenance guys are in another town-not sure if they have company emails etc...

 

[Jeetyet]

Sounds like you've about covered all the bases you can for now. Hope you get a resolution soon.

 

[athan01]

Got a call from the pool company. They are puzzled with what they have seen in the picture. The guy I talked to, initially thought that it was something simple but after looking at the picture he decided to get the guy who installed the tiles, together with himself and another guy, to check the pool on site to decide what it might be. This will happen sometime next week.

It will be interesting ....

 

[I Know Nothing]

Hi Jeetyet:

The only experience I have is as follows: I assisted friends with grouting a pool (we used unsanded grout) and the experts are not kidding when they say clean your tiles immediately after applying the grout (if you don't, it will dry like cement) while sanded grout will wipe off with a damp rag after setting. That was a hard lesson but learned quick.

My only other experience with building materials came while working for an engineering firm. They needed a woman in order to acquire a contract for the building of a new waste water treatment plant and update to the cities infrastructure. They knew me from services I provided them (cleaning) and put me back in the laboratory where I became acquainted with the testing of building materials through the ASTM (American Society for Testing Materials) manuals. In these manuals you can find the characteristics/limitations of all materials used in construction of everything. (they had it for condoms). lol

If it weren't for these standards, your pool walls would collapse, your linings would tear, your spring board would collapse beneath you and your over weight friend would break your fiberglass slide and your beautiful concrete deck could crack or settle. (We won't get into the behind the scenes construction standards of your IG pool because that was just too much when I glanced at it) Holy Cow will have to do.

To make a long story short, I discovered what soils were comprised of and sand is in the mix unless your lining a landfill (high graded clay is a necessity) It's not hard to spot it when you see it and although high winds were brought up, the sand would also be lying at the bottom of the pool and I imagine driving winds with that kind of force would put some pool water on the deck. That leaves grout as a suspect. (barring any chemical problems which I am just learning about).

I'm just as curious as you!

Sorry athan01, I should've clarified that my questions were aimed towards some of the previous responders. I was hoping for some further input/clarification for the both of us from those who seemed to have some experience with this issue. Hope you get it sorted soon. Will keep an eye on this thread just to satisfy my piqued curiosity.

 

[athan01]

The pool company, called back and arranged a meeting on site, with the subcontractor that installed the tiles on the pool.
The subcontractor immediately understood and said what the issue was :

The glue as they call it, that they used to stick the tiles into the concrete walls of the pool would squeeze out on the gap between the tiles when the tiles would be pushed towards the wall. In an ideal world they immediately clean that as much as possible, but in the real world they do not clean it deep enough. This would cause the depth of the gap between the tiles to sometimes be deep and sometimes very shallow (and sometimes not even be a gap but the glue sticks out higher than the tile).

Later on when they do the grouting using the white sealant material, the layer of the grout would sometimes be thick and sometimes be very thin (almost as thin as a layer of paint). Well.. in those cases where the sealant was very thin as a paint, it comes off after a few months/years.

How to solve the issue: The pool must be emptied, the grout between the tiles must be removed (not completely but up to the point where it will have enough depth) and then reapply the sealant.

The pool company will have some internal discussions and come back to me. The subcontractor and the pool company are expected to cover all the costs.

 

[Jeetyet]

Glad you got it sorted! Sounds like a lot of tedious work to fix the problem, but at least they are willing to fix their mistakes.