brown spot on bottom of pool w/pics

[hchc]

Hello, potential first time pool owner here
A pool at the house I'm looking at has a few brown spots at the deep end of the pool near the bottom. The biggest is about baseball size. Goggling mostly points to rebar rust, and I just learnt it might just be a surface stain "dirt scale"?...

I took some photos so what to get some expert opinion here:
If it is rebar rusting thru..how much am I looking at?
If it is just surface stain, what do i use to get rid of it? Thanks in advance!

zoomed in

another spot

 

[zea3]

It's hard to tell just by looking what type of stain it is. That last picture looks like it has a raised edge. Some stains can be taken care of with raised chlorine levels and brushing, but the stain will need to be tested to find the cause and figure out a solution.
If you can find out some of the pool's maintainence history and current test results that would help.

 

[JohnT]

If it is just a surface stain, a vitamin C tablet will remove it.