Had an algae problem develop when I didn't have the time to devote to our vinyl pool that was needed. The wife took a water sample into the local pool store, and after they ran their test...nothing really surprised me except for the Calcium levels. According to the store people...the calcium levels in the pool are too low for the pool...and that some calcium is required to "keep the liner conditioned". Went back through pool school and the level on one page was 50-300, yet another page said calcium wasn't really necessary in a vinyl lined pool. If I'm remembering correctly...my wife said the level was around 10. I'm hoping someone can please clarify the role of calcium levels in a vinyl lines pool. Thanks a bunch.