How to get rid of these spots on pool floor?

[Alexr54]

I tried to use some hydrochloric acid on the pool floor. This is in the deep end, so got one of those sticks with the acid holder on the end.
Didn’t work.

It looks almost like dirt. But it’s not. It won’t come out no matter what I have tried so far.

 

[1poolman1]

Try some calcium hypochlorite sprinkled on the spots. With the pool off, sprinkle right above the spots and let it settle. Let it set there for a while at least 15 minutes, or even until it dissolves (if you can wait that long). If it is organic the chlorine will remove it.
Cal hypo is normally packaged in one-pound pouches as "shock," but be sure it is cal hypo not sodium dichlor. You can get larger quantities but it may not be compatible with your chemical regimen.
Don't get it on your clothes. Stay upwind from the dust as it will bleach your clothes as well. If it doesn't work, you've added a bit more chlorine and a little calcium, won't hurt anything.
If it does work, be prepared for the spots to come back and keep treating until it stops.

 

[Katodude]

Looks like black algae to me. Can you get something to pick at it and see if you can remove one of the dots?

 

[Alexr54]

Try some calcium hypochlorite sprinkled on the spots. With the pool off, sprinkle right above the spots and let it settle. Let it set there for a while at least 15 minutes, or even until it dissolves (if you can wait that long). If it is organic the chlorine will remove it.
Cal hypo is normally packaged in one-pound pouches as "shock," but be sure it is cal hypo not sodium dichlor. You can get larger quantities but it may not be compatible with your chemical regimen.
Don't get it on your clothes. Stay upwind from the dust as it will bleach your clothes as well. If it doesn't work, you've added a bit more chlorine and a little calcium, won't hurt anything.
If it does work, be prepared for the spots to come back and keep treating until it stops.

Thank you I’ll give this a try.
This is a salt water pool. I don’t add any chemicals. The pool is always very clean and clear. It’s just this one spot I can’t seem to get rid of.

 

[Donldson]

This is a salt water pool. I don’t add any chemicals.

Please tell me that you're not saying you ignore pH, TA, CH, and CYA...

 

[Alexr54]

Please tell me that you're not saying you ignore pH, TA, CH, and CYA...

I test regularly.
I have never needed to add chemicals to get levels correct. Sometimes I super chlorinate using the salt cell. That’s it.

 

[Alexr54]

The calcium hypochlorite shock worked wonders on those spots!
They are now completely gone. Thanks!!