Do I need a new filter?

[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 may 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?

[Denniswiseman]

Sometimes it's best to bite the bullet and just go for a new filter when you have problems
Yes go for a larger one as slower filtration works better, which you can do with your pump
If you go for a chlorinator get a salt water chlorine generator (SWCG) twice the size that you need as the output is rated using it 24/7 at 100%
So long as the pump is filtering you will be introducing chlorine reducing maintenance
The puck type dispenser introduces CYA which in excess renders your chlorine ineffective
For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm
While you're at it you really need to get yourself a decent FAS/DPD test kit (Taylor K2006c or TF Testkits TF100 in the states) to get accurate results
Usefull reading
Chlorine / CYA Chart
Recommended Pool Levels
Pool Maths