Just saw your PM, sorry I did not respond earlier. I don't know if you solved your problem but a couple of observations:

I am not an expert on DE filters so I cannot offer much help there. However, if there is a way to operate the filter without the grids, you can check if the pressure is coming from the grids or not. If not, then you can look other places.

A couple rules of thumb regarding pressure and suction:

Low pressure readings can mean low restrictions on the pressure side (good thing) or high restrictions on suction side (not a good thing).

High pressure readings can mean low restrictions on the suction side (good thing) or high restrictions on pressure side (not a good thing).

Point is you cannot tell from the pressure reading alone if you have a problem or not. Valve settings will have an effect on filter pressure so try different settings to see if the pressure you noticed before was due to a particular configuration:
Pool Mode
Spa Mode
Spill over Mode

As I mentioned before, your turnover is currently about 4 hours. Most you would need would be 8 hours during the peak of the summer. Any reason you are running the pump 10 hours?

Blowers do not make up for low HP pumps so you do not want to lower the HP of the pump unless you plan on having a separate pump for the jets. So your options are:

1) 2 Speed 2 HP pump replacement. Reduce your power bill by 69% with 8 hour run time at low speed.
2) 2 x 1 speed pumps. Re plumb 2 HP pump for Spa Jets only and purchase a 3/4 HP pump and plumb from for pool only. Reduce your power bill by 67% with 6 hour run time.
3) Reduce pump run time for current configuration. Reduce your power bill by 20%.