Gunite Pool; Is this Scale, Calcium, Metal or Just Worn Out?

[Dennis in CT]

Hello All - Just discovered the site and hoped you all might be able to help. Purchased the house about 7 years ago and pool was already built. There was already some of the white discoloration you see in the attached pictures, but over time, it has gotten much worse. Never bothered me too much but now getting to a point where there is almost as much white as there is meant to be dark blue (especially on the shallow end). So is this scale, metal, calcium or just normal wear? My water comes from a well over 300' down and while tasty, is rather hard (400) so I wondering if that might contribute to the problem. Would love to hear what it really is and if it can be remedied and how. Afraid I am going to hear that it will need to be re-plastered......Ugh. How much is that for a 15' x 40' pool? I dont think I want to know.

Many thanks.

 

[gilbee]

It kinda looks like scale to me, what are your test results?

 

[Dennis in CT]

Yesterday it was:
Alk 40
PH 7.2
FC 10
HDR 100
CYA 30

 

[gilbee]

What is HDR? Calcium hardness? What kind of test kit are you using?

 

[chiefwej]

What does the surface feel like...does it feel sharp and almost prickly, or just kind of rough?

 

[jblizzle]

So the pool is supposed to be the dark blue? And the white is raised off the surface? If so, certainly looks like scaling.

 

[Michael1]

It may be mottling. See this post.

http://www.troublefreepool.com/threads/54515-White-Spotting-of-New-Plaster-Pools

I have some in my pool, and it appears many or even most pools with colored plaster have this to some extent. There are other colored finishes that are more uniform.

 

[JamesW]

It looks like the pool was originally plain white marble plaster and the turquoise and black is from heavy copper staining.

Google pictures of copper stains in a swimming pool.

If you scrape off the top layer in a test spot, you should be able to determine the plaster's original color.

 

[Dennis in CT]

Thanks to all. This morning I decided to finally take a closer look. Went under with goggles and found that yes, the spots are not smooth, but more like sandpaper. But was surprised me was not only are they rough, but they are like small craters as if the plaster has deteriorated. I found other stuff on the net similar to what Michael1's post says, so at this point I am figuring it needs to be replastered. Not in this years budget so it will have to wait. I guess my next question would be how much is that going to cost. There are no cracks....do they still need to remove the old plaster or just go over the current? Thanks again for all the comments.


Sent from my iPhone using Tapatalk

 

[kadavis]

One of the most severe cases of spot etching I've ever seen, along with the copper staining. Would do a complete chip out and replaster. If you can afford look into pebble tec or color quartz

 

[Girl on the edge]

A total alkalinity level of only 40 is a very corrosive water. From the photos you have provided it looks to me like your water has had low TA for a very long time. What it looks like to me is that your colored plaster has been eaten away by this corrosive water and is exposing the layers of material that is under the plaster. I am going to say that I would look into a re-plaster job and once that is done I strongly suggest making sure your water is balanced correctly from that point forward. Bad water chemistry is the number one reason for premature equipment failure. If the water is doing this to the surface just imagine what it is doing to the inside of your equipment where you can not see.

 

[JamesW]

I think that the plaster is white with copper staining. I think that the white is reappearing as the plaster deteriorates and the stained layers dissolve.

 

[onBalance]

Michael is correct. This is a typical dark colored plaster that is also probably suffering from a second mistake.
The original problem with the plaster is known as white porous or soft spotting (also incorrectly called "spot etching" by some). See link that Michael posted.

First, the plaster crew adds too much calcium chloride (hardening accelerator) to the plaster mix so that it takes less time to complete the pool. That leads to the plaster hardening too quickly before the plaster surface can be made smooth, then the finishers splash water onto the plaster surface and trowel that water back into the plaster surface to make the surface smooth. That is what led to the original problem of spotting.

The defective plaster surface caused by the above issues leads to porous areas or spots that will soon lose the pigment color within the plaster when submerged in water. Porosity also lightens the color of all plaster finishes. It usually takes a some months to whiten if the water is generally balanced, but the white spots will remain as smooth as the surrounding (dark color) areas. If the water is aggressive from the start, then the white spotting will occur much faster.

The second problem, and as you determined for yourself, the white spots are now rough and pitted. That means that the pool water has been aggressive, at least for a period of time. That is why the defective plaster spots are now rough, sunken, and pitted. However, I will say that since the pool is at least 7 years old, the deterioration and erosion of those defective white areas or spots could be simply from long term wear of being submerged in balanced water. But your water tests indicate aggressive presently, so it is hard to tell what role the aggressive water has played in that pool, but aggressive water will certainly make the surface pitted and compound the problem.

A re-plaster company would probably either remove the old plaster, or etch the plaster surface by acid or sandblasting, and then place a new plaster coat job over the top.

 

[onBalance]

Dennis, while the plaster is obviously old and worn out and you will eventually have it re-plastered, It would be interesting (for all of us TFP members) to have the plaster surface scraped and remove a thin layer (in eighth of an inch thick) of plaster (about a square inch of surface area) to see if the plaster color is "white" under the "dark gray" color plaster, or if it remains dark. This was James' suggestion above as a way of determining the actual color of the original plaster. Would you be willing to do that and report back? Thanks.

 

[Dennis in CT]

Yes, I can do it some day this week with some pics. I realized I also have a go-pro with an underwater shell so I can get some better, close up pics. Is there any one on this board in Litchfield County, CT? I need to figure out who I am going to get to re-plaster this thing.

 

[JamesW]

What information did the original owner provide about the pool?
How old is it?
Has it ever had a heater or used a copper ionizer?
Did they say what the original color was?