I'm interested in this too. My CH was 170 and I have a SWG gunite/plaster pool. Someone recommended bumping it up some to at least 250 so I don't leach Calcium from the plaster. The previous owner must have been adding Calcium routinely bc he left a big 5 gallon bucket of it. I had some scaling around my waterfalls (moderate amount) and minimal amount on the tile line, but I don't know if that can be attributed to the previous owners letting the pH routinely become too high. It was at 8.0 when we first moved in about a month ago. Since then I've brought it down to 7.4 and now I'm questioning whether or not I should up the CH?