Sorry for the poor picture quality, took the pic zoomed in while the sun was getting low. But one day I noticed a significant amount of spots on the bottom of my plaster pool. Seemed like they appeared out of nowhere - I have a weekly pool service so chemistry should be in check according to my testing.
When I literally touch the spots with my feet, they are raised and hard, seems like it is not so much a stain but literally something hardened on the floor.
So my question is, is there any harm in me putting some goggles on and going down there with some sort of putty knife and attempting to scrap the spots off? And if I choose this route anything I should do in preparation?