I am hoping you all can help me ID a stain. First a little history:
Over the winter a few of our looploc pool anchors became dislodged from the wall during a heavy snowstorm. It didn't seem to let in too much extra debris but when I opened the pool in mid-May I noticed the heavy staining you see in the pictures this was not there at all at the end of the season or during any of the other seasons. The plaster is starting to degrade some but still probably had/has another season to it before it need to be resurfaced (at least in my opinion). The stains and surface are now very rough and seem to be calcium deposits but I am not sure and wanted to ask the forum. If they are indeed calcium, is there anything I can do short of sanding them down, acid washing or resurfacing?
Also, I have tried Vitamin C, so I don't think its a metal stain.
Thanks in advance!