Growing black spots, and hairline crack questions

[poweranimal]

-pool background
22 year old quartz finished plaster
15k gallon kidney

So my main question, is these black spots forming. I acid washed the pool over the winter and tried removing them with a bath of different chemicals and scrubbing, but nothing worked. Thinking it was algae, I poured a whole bottle of algaecide once the pool was refilled only to notice it grew faster.
How do I remove these?

-next question. In the picture you might notice my poor attempt to seal hairline cracks around the steps. As more cracks are forming, what’s the best method to prolong its already depleted lifespan?
My thought is that eventually the pool will crack faster than I can repair them and that’s when I get it resurfaced? Or just let it be until it starts losing water?

Thanks folks!

 

[Bperry]

-pool background
22 year old quartz finished plaster
15k gallon kidney

So my main question, is these black spots forming. I acid washed the pool over the winter and tried removing them with a bath of different chemicals and scrubbing, but nothing worked. Thinking it was algae, I poured a whole bottle of algaecide once the pool was refilled only to notice it grew faster.
How do I remove these?View attachment 583155

-next question. In the picture you might notice my poor attempt to seal hairline cracks around the steps. As more cracks are forming, what’s the best method to prolong its already depleted lifespan?
My thought is that eventually the pool will crack faster than I can repair them and that’s when I get it resurfaced? Or just let it be until it starts losing water?

Thanks folks!

The black spots look like the failed plaster I had in my pool. They were super soft mushy plaster with alage mixed in. If you were unable to scrub them away then it may be something different but they look like failed plaster to me.

Unfortunately, cracks (other than spider cracking) ususally mean the water is already leaking especially if cracks are growing. Leaking will lead to more cracking and more leaking until…

 

[poweranimal]

The black spots look like the failed plaster I had in my pool. They were super soft mushy plaster with alage mixed in. If you were unable to scrub them away then it may be something different but they look like failed plaster to me.

Unfortunately, cracks (other than spider cracking) ususally mean the water is already leaking especially if cracks are growing. Leaking will lead to more cracking and more leaking until…

My water bill is unusually low (2,000 gallons last month), so I doubt it’s leaking yet. Cracks arent really “growing” as the number of them increasing. They are all hairline cracks….so far . Thanks for the reply!

 

[Bperry]

My water bill is unusually low (2,000 gallons last month), so I doubt it’s leaking yet. Cracks arent really “growing” as the number of them increasing. They are all hairline cracks….so far . Thanks for the reply!

Beware of using the water bill as a guide. Itll detect gushing leaks from a sprinkler system, but slow seeping leaks of a few gallons per day can do a lot of damage before they become detectable. I had a couple hairline cracks for a year or two before they started multiplying. But that time the gunite underneath was damaged and the pool started losing a more noticable amount of water. I posted some pictures in a renovation thread last year.

The kind of spider/check cracking thats usually deemed “normal” are kinda random small cracks that eminate out in various directions an inch or two.

Cracks you need to pay attention to will tend to be longer and not change direction very sharply, or travel across multiple surfaces. Those tend to indicayr a crack in the underlying gunite which will leak water, but how much will vary on how large it is.

 

[poweranimal]

Beware of using the water bill as a guide. Itll detect gushing leaks from a sprinkler system, but slow seeping leaks of a few gallons per day can do a lot of damage before they become detectable. I had a couple hairline cracks for a year or two before they started multiplying. But that time the gunite underneath was damaged and the pool started losing a more noticable amount of water. I posted some pictures in a renovation thread last year.

The kind of spider/check cracking thats usually deemed “normal” are kinda random small cracks that eminate out in various directions an inch or two.

Cracks you need to pay attention to will tend to be longer and not change direction very sharply, or travel across multiple surfaces. Those tend to indicayr a crack in the underlying gunite which will leak water, but how much will vary on how large it is.

Just got out of the pool again. I did notice the black spots are all forming from a crack.

 

[Bperry]

Just got out of the pool again. I did notice the black spots are all forming from a crack.

That likely means water is getting under the plaster layer.

 

[poweranimal]

That likely means water is getting under the plaster layer.

I’ll have to cover it up with something then. I’m no pool expert, but the rest of the plaster looks like it has several years left. I imagine I could just use concrete injection and paint the whole pool with Super Quick Seal. I’m sure that would give me at least 5 more years before a demo is needed.

 

[Bperry]

I imagine I could just use concrete injection and paint the whole pool with Super Quick Seal. I’m sure that would give me at least 5 more years before a demo is needed.

Unlikely to last that long judging from ofher experiences with painted on coatings.