Calculating head and proper filter pressure

[Water_man]

I have the original blue print that was designed for a ¾ HP pump and a 26 SF filter.
As mentioned before, the previous owner upgraded to 38 SF filter and 1 HP pump.

On the blue print, the specs say in writing two ¾” return lines. The outlets are definitely ¾”. However, above ground (see pic) only one 1 ½” return is visible (the other one is the auxiliary Polaris line which I use now as an additional return line). On the blue print diagram you see one return line branches into two return outlets. This means there are two possibilities that can be verified only by digging:

Either there’s one main return line of 11/2” which is parallel to the pool edge, from which two
¾” returns T –off to the pool, or, the 11/2” main return line splits in the ground near the pad to two
¾” lines

The vacuum line is definitely 1½” and so is the Polaris line (which now serves as my additional return.)

Distances from pad (in feet) :

Skimmer : 28

¾” returns:

Near : 32
Far: 44

1 ½” return : 35

Filter pressure (PSI)

All returns open: 8
Only 1 ½” open : 14
11/2” open and either one of ¾” open : 10.

The flow rate is visibly higher than what I had before with my “sick” 1 HP Anthony pump.
Since I’m not accustomed to such a vigorous flow, I wonder if it’s within the acceptable limits.

Above ground plumbing pic: