Pump: Pentair model SF-N1-1-1/2A/340039 = 1.5 HP Pentair SuperFlo (curves)
Filter: Pentair Tagelus, Part #145241 = TA60D 24" top mount sand filter, maximum desirable flow, 45 GPM

To give you a comparison, I run a 36" filter (2x the filter capacity) with a 1.5HP Hayward Super pump which has the same curve as your pump . . . and it is PLENTY big enough, even though it has to run a high restriction fountain!

You'd probably be better off replacing the impeller, diffuser, and seal, and dropping back to 3/4 HP performance. You'd cut your electrical bill by 35% or more . . . and you'd be able to filter fine particles. As it is, you have so much flow and pressure, you just force the fines through the filter!