Black plaster marks

[dphanes]

We have a new gunite pool. There are several black marks on the plaster. Water chemistry is good so I don’t think they are black algae.
Any thoughts on what they could be?

 

[ajw22]

How new? When was the water added?

 

[Dirk]

If the finish is still under warranty (and you've confirmed it's not algae): balance the water as per PB's spec's, and then call the PB for a warranty repair. I had a similar mark in my pool, and the PB sent out a guy who got in and took care of it. Nice.

If you attempt a DIY repair, however harmless it might seem, you might void your warranty. You want the pool's chemistry to be inline with what the PB expects, so that he doesn't use that as an excuse to avoid dealing with the issue.

 

[dphanes]

If the finish is still under warranty (and you've confirmed it's not algae): balance the water as per PB's spec's, and then call the PB for a warranty repair. I had a similar mark in my pool, and the PB sent out a guy who got in and took care of it. Nice.

If you attempt a DIY repair, however harmless it might seem, you might void your warranty. You want the pool's chemistry to be inline with what the PB expects, so that he doesn't use that as an excuse to avoid dealing with the issue.

Did you ever figure out what it was? Trowel mark?

 

[YippeeSkippy]

What are the white specks? They look like undissolved chemical product- not good letting it just sit on the surface as some chemicals can mar the finish.

Maddie

 

[dphanes]

What are the white specks? They look like undissolved chemical product- not good letting it just sit on the surface as some chemicals can mar the finish.

Maddie

reflective pieces. It is Aruba Sky Relections Quartzscape

 

[dphanes]

How new? When was the water added?

40 days ago

 

[ajw22]

My guess is dirt that got embedded in the surface of the plaster. What depth is it?

 

[dphanes]

My guess is dirt that got embedded in the surface of the plaster. What depth is it?

That is deep end but there is some in shallow end too

 

[ajw22]

Talk to your PB about the marks and see what he says.

 

[Dirk]

Did you ever figure out what it was? Trowel mark?

Mine was not elongated, so not a trowel mark. At first I panicked because it looked like rust, so I thought maybe rebar rust, but it wasn't (though that is possible when rebar is too close to the surface of the finish). I think it was probably just impurities in the pebble mix. Maybe a flake of iron or a pebble with iron in it, that rusted. I missed watching the repair, but it was pretty fast. And it didn't seem like it was a mystery to the PB or his worker, which made me think it was a semi-common occurrence. I had just the one spot, and it didn't come back.

Are your marks in any sort of pattern that looks like your rebar grid? Doesn't really matter, that's what warranties are for.