About a week ago I noticed what looks like calcium scale on one rock near my pool. Thing is, the white marks are way above the water line. This rock is near (within 2' of) the area where I drop chemicals (Cl, HCl, etc...).
Is it possible these white marks are damage caused by muriatic acid? If so, how can I prevent this from spreading? I've already brushed the rock and sprayed with copious amounts of water. (After brushing, the white marks disappear for a while, then reappear after the water dries.)
Here are some pictures.