Sand Filter PSI question- new pump a little disappointing

[simsjim]

Good day

First some Pool Stats:
12K gal IG vinyl - Old AnthonySylvan "Vacationer"
2 skimmers/main drain
2 pressure side outlets
1.5" plumbing
-uphill climb from the pool to the equipment pad (which is about 30 feet away from the pool)

Old Pump/Filter set up
Hayward SuperPump ¾ HP
Sand Master 19 100# Top Mount Sand Filter

New Pump/Filter set up:
WhisperFlo ¾ HP EE Full-Rated pump
Taglius 60D 325# Top Mount Sand Filter

I just replaced my historically significant SandMaster 19” top mount Sand filter (100#) and Hayward ¾ hp SuperPump with new hardware. I now have a Pentair Whisperflo Full-Rated EE ¾ hp pump feeding a Pentair Taglius 60D Top Mount sand filter (325#).

In my previous set up, my 35gpm (@ 60 ft of head) SuperPump forced the filter to sustain around 12-15 PSI under normal conditions. With the new set up, the WhisperFlo (which is rated at 60 GPM (@ 60 ft of head) is creating a filter pressure of around 8 PSI. – significantly less than what I am accustomed to seeing.

I guess I am curious about opinions on this operating pressure. Is this something I should be concerned about? Is 8 PSI too low for a “High Rate” sand filter? I wonder if I should have gone with a 1 HP Whisperflo. But when I was researching pump/filter configurations, my main concern was the GPM at my given head and the matching max GPM of the Taglius 60D.

I think I am beginning to discover the GPM flow curves are more “academic” or theoretical than I assumed, and that perhaps there is wide range of circumstantial variance within the curves. – Is this true?

When I purchased a pump that was seemingly capable of moving twice the amount of water as my previous pump, I suppose I expected to see a notable increase in the suction rate at the skimmers and main drain. But the rate of suction seems to be disappointingly similar to the rate using the SuperPump.

So I guess my two main questions would be:

Is this PSI normal given the configuration, or should it be higher?

What is your opinion on using a 1 hp instead of a ¾ HP WhisperFlo – would the additional HP create more intake suction, allow for increased operating pressure, but avoid channeling and the other fun stuff associated with oversized pumps? Pros/Cons of a larger pump? Sometimes bigger is not always better, and hearing some opinions of more experienced folks would be beneficial.

As always, thanks for reading.

Peace