Stains in gunite pool

stfbr

New member
May 13, 2020
1
Spring/TX
Hi everybody,

I just got my first pool (gunite) and I would like to do the cleaning by myself. There are some strange stains at the bottom. I brushed the area but nothing changed. Any ideas?

My readings are as follows:
pH : 7.6
TC: 5
Total alkalinity: 110
Hardness: 500

Thanks in advance.
 

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