As newbies at pool care, what can we do to prevent white scale from building up on marble slabs along the edge of our pool? Our water in AZ is very "hard" and the marble was sealed with Hydrex by Tenax. We currently have a sand filter and are using chlorine without an SWG. One installer has recommended adding a water conditioner and changing to UV sanitation with enzymes, an ozone system and DE filter. All at a hefty price when we simply want to stay ahead of the build up issue.