Had a BAD experience With pH lock. My calcium levels seemed to be good, but when I added the pH lock, it turned the water to "milk". Had to drain the tub and had a gooey paste all over the filter and a chalky residue all over the tub. The folks at Leslie's were stumped, say they've never seen it that bad before. The only explanation is that the water was too hard. Any ideas would be appreciated, but I'll probably just avoid any phosphate buffers from now on.