I having being using TFP for quite some time and have never seen this and I searched around but could not see anything related... thus, the new post.
The sunshelf on my SWG pool is 9" deep and the spa waterfall does overflow onto it. Recently, I have found ~10 black, RAISED spots on the sunshelf (see photo). They are hard as a rock, including the black top. They are raised up about 1/4 inch, maybe a bit less, and are about 1/4 inch in diameter as well. Scraping the black top does not remove anything unless you really tear at it with your fingernail. I smeared it on white paper and it does not smear at all- thus unlikely to be black algae or any algae really.
When I did get a bit more to scrape off the substance under the black top appears to be plaster. It is like the plaster is rising up in these strange bumps. I showed them to my pool guys with 30 years experience and he has never seen or heard of anything like it. He says definitely not algae and advised me to call the company that built our pool. That will be expensive visit and my faith in them is LOW...
I have attached a photo but you can't see much here- they are the 3 larger black dots on the plaster. Does anyone have any ideas what these may be? The cause? and how to treat them?
I believe my chemicals have been in very good balance for a long time. Current chemical readings from my Taylor kit are:
Hardness: 430
FCL: 7.8
CCL: 0.4
pH: 7.5
Alk: 80
CYA: 65
Thank you so much!!
The sunshelf on my SWG pool is 9" deep and the spa waterfall does overflow onto it. Recently, I have found ~10 black, RAISED spots on the sunshelf (see photo). They are hard as a rock, including the black top. They are raised up about 1/4 inch, maybe a bit less, and are about 1/4 inch in diameter as well. Scraping the black top does not remove anything unless you really tear at it with your fingernail. I smeared it on white paper and it does not smear at all- thus unlikely to be black algae or any algae really.
When I did get a bit more to scrape off the substance under the black top appears to be plaster. It is like the plaster is rising up in these strange bumps. I showed them to my pool guys with 30 years experience and he has never seen or heard of anything like it. He says definitely not algae and advised me to call the company that built our pool. That will be expensive visit and my faith in them is LOW...
I have attached a photo but you can't see much here- they are the 3 larger black dots on the plaster. Does anyone have any ideas what these may be? The cause? and how to treat them?
I believe my chemicals have been in very good balance for a long time. Current chemical readings from my Taylor kit are:
Hardness: 430
FCL: 7.8
CCL: 0.4
pH: 7.5
Alk: 80
CYA: 65
Thank you so much!!