What is this on the cement?

[LisaBgame]

I’m looking for input on what this is and how to get rid of it. It’s only on the cement in the deep end.

 

[JamesW]

Maybe iron.

Is this new or old?

Put some vitamin C on a spot to see if it makes any difference.

What happened with your heater?

 

[LisaBgame]

When you say vitamin c , do you mean like the supplement or is there a special industrial strength? Oh! And the heater got replaced thanks to a very generous gift from my step-dad!

 

[JamesW]

Regular vitamin C or ascorbic acid.

 

[OntarioCanada]

When you say vitamin c , do you mean like the supplement or is there a special industrial strength? Oh! And the heater got replaced thanks to a very generous gift from my step-dad!

Supplement tablets, I have used them to take off rust marks from liner. Works.