Mrfoamy

I inherited my house 10 years ago and it has a 18,500 gallon in-ground pool with a Purex 2048 DE filter and Pentair VS-3050 pump. The backwash valve has been frozen in the filter mode for at least 10 years. My service company cleans it 3 times/year and changes grids as they fail. There are two issues of concern: First, the service people show up outside our bedroom unannounced, which my wife hates and; Second, if the ancient backwash valve fails it will create a crisis, and I travel a lot. My idea is to install a new cartridge-type filter to avoid a failure crisis. Any opinions on installing the largest filter possible? It would give several advantages: I could clean it myself, only twice a year or less, since it has a larger surface area. With that larger surface area couldn’t I run fewer hours and use less electricity? I’m looking at the Pentair Clean and Clear Plus 520, about two sizes up from standard. A related question: One contractor recommended a chlorinator, even though we have copper pipes. He says there is no problem with that even though Leslie’s says not to. I can see the advantage for him since his employees don’t need to carry around bottles of chlorine. Thoughts?