rust on lower level wall

[tcbdab]

I am replacing my pool liner (18x32x52). I have the liner out but have encountered a rust issue I was not expecting...
I have not had any leaking issues at this end of the pool. Though this is the part that gets the most shade. I was not able to poke a hole through the wall so it may just be surface rust. any suggestions would be greatly appreciated : )

 

[kellyfair]

That’s a LOT of rust. Have you tried brushing it to see how thick the layer is?