I’ve reached the point of replacing my pool pump & filter. The old one is a single speed with a sand filter. I’d like to have a Pentair variable speed pump and their cartridge filter. I’m just a little bit confused on which version of either I need there are several different types of Pentair variable speed pump‘s etc. The pool is approximately 24,000 gallons a rectangular shape with a diving half and the play/shallow half. I had heard you should buy a larger filter than you need but again just looking for advice on which version I should be looking at. Would this also be a good time to convert the pool to saltwater or should I wait to do that once I have the pool interior refinished (it’s shot too)? Thank you for any advice some of you pool expert’s could provide.