u/MedicalRespond1602

Ok I recently took over my mom's house because she is sick. My brother and his family lived with her and ran the house....and pool in the ground. So these are pictures of the pool when I moved in and then I have a picture of it after. Which is leaps and bounds better and swimmable but there are dark patches that a shock, algaecide, and wire brush can't get off? And suggestions on what I can do to get rid of these patches ?