I needed to add a gallon of acid to my pool today. I have a 3-4' high tile wall spilling into a surge pond for the pump suction. There was some calcium build up on one section of the tile wall so I poured the acid down the wall to burn off the calcium. I used 14.5% HCL (Muriatic Acid) and now wondering if this is not advised. I flushed the tile afterwards and the acid removed the calcium very nicely. I expect it is probably doing some damage I didn't see. The surge pond is probably about 250 gallons so the pH dropped pretty low in the surge until it was all flushed out. What other damage might I be doing with pouring acid on a tile wall?