Black Algae vs Gunite

[Pool Fool 2]

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Here you go. Thanks for your patience. I don't have any mariatic acid but will get some.
Thank you!

Do these pictures help? The colors of whatever this is range from black/brown to tan. The tan horse shoe shape and blob are the largest tan places in the pool

 

[SoDel]

Taking another tack, have pine trees nearby? Could it be hardened pine sap?

 

[Pool Fool 2]

Taking another tack, have pine trees nearby? Could it be hardened pine sap?

That is an interesting idea. There are many trees around the pool, but no pines. One of the challenges with this pool is all the shade. I didn't know pine tree sap would do that to a pool. Thanks for your thoughts.

 

[Bperry]

View attachment 438172View attachment 438173View attachment 438174
Here you go. Thanks for your patience. I don't have any mariatic acid but will get some.
Thank you!

These pictures look like normal algae or plaster worn down to the gunite. I have similar looking spots, but mine are definately worn away plaster.

 

[Pool Fool 2]

These pictures look like normal algae or plaster work down to the gunite. I have similar looking spots, but there are defiantly worn away plaster.

Thanks! The pool company said that this is worn down to the gunite, though they came today and told me they didn't know what it was... What parts of the picture are the worn away plaster? the black spots, the tan spots or something else? I can take a wire brush and brush the same spot 10 times and see no difference at all...
The yellow spots vary between being same level as the plaster to being like long grained rice on top of the plaster in places.

I took a screwdriver out today to try and take off the tops of some of the black spots, and it was sharp and very hard and would not come off...

I haven't been able to find any pictures of gunite that look like my pool. It's good to hear from someone that they've seen something like it. How are you treating your pool with this issue?

Thanks very much for your help!

 

[Bperry]

Gunite looks black or dark gray. Kinda like wet cement since that’s what it is. Though the black part should be a low spot if it’s gunite. Some of the tan or green stuff can just be organic stains from leaves or it could be iron staining. Raise the chlorine up to slam level for a few days to a week and see if any of that goes away.

 

[Pool Fool 2]

Good night looks black or dark gray. Kinda like wet cement since that’s what it is. No the black part should be a low spot if it’s gunite. Some of the tan or green stuff can just be organic stains from leaves or it could be iron staining. Raise the chlorine up to slam level for a few days to a week and see if any of that goes away.

Thanks. We've nuked it several times, once for about 4 days. No change at all in any of it. When the pool was opened it was drained then power washed with a strong chlorine solution. Since then, about a month ago, we've hit it hard and often with chorine, but no noticeable changes in the pool at all.

 

[mknauss]

or it could be iron staining.

This pool has had a copper/silver ionization system on it.

 

[Bperry]

This pool has had a copper/silver ionization system on it.

Ah. Didn’t realize that. Metal staining starts to make more sense than black algae.

 

[Mike408]

Pool fool the tan pieces I believe to be calcium nodules.

I could be wrong.

Calcium Nodules – Pool Help

 

[duraleigh]

That pool surface may be too difficult to restore. You may end up throwing good money after bad. I would get an estimate on replaster