Cartridge size for 13,000 gallon pool?

I have a sand filter at present which gives me no end of trouble. The problem is due to the native vegetation (gum trees and similar) which regularly drop fine hairlike flowers. These get into the filter and form a mat across the media. Backwashing does not remove this mat of hairs, and I end up having to open the filter every few months to clean it out. Filter socks successfully catch the hairs but I have clean the skimmer and sock once a day which is too much hassle.

I want to try a...

Cartridge size for 13,000 gallon pool?