What could it be exactly?
I don’t need help, but I’d like to get assessment to figure out what this exactly is. When I moved in, the shower enclosure were full of it (at least the corners). It was looking like crystals, which grew over. I could remove it with a scrub brush and some normal all purpose cleaner. However, have year later I see this coming back. It is only in the shower enclosure, any other sink in the house does not have this issue. Our water in this area is low in lime. I am also wondering where the brown red color is coming from. Any ideas?