Would it be beneficial to drain the dirty-water from the pressure-side of a PLD70?

Dynamic pressure is 4-psig, so media replacement is not warranted.

Thanks!

Do you have a 2-speed or variable speed pump?
What rpm is that pressure at?

It's usually not required to do anything to the filter until it's time to clean it. Then you clean and recharge it.

Thank you for your interest.

Filter-pressure is 4-psig when the pump is rotating at 3450-rpm. Have ordered a replacement pressure-gauge. Motor is a single-speed 'special-purpose' model by Emerson, rated 1-hp, and drawing less than half of the rated-current. The impeller is rated for 3/4-hp, and the piping is 2-inch throughout.

Planed to drain the filter while the pump was not running. Filter is performing well, but the pressure-side water is quite turbid, and has a greenish color.

Sounds like you have algae starting. You need to shock.
can you provide us a full set of test results?
pH
FC
CC
TA
CH
CYA
Salt

FC = 2.5, CC = 0.2, KH = 120, GH = 290, CYA = 50, NaCl= 580

Concrete pool, Chlorinated by Tri-Clor generator. Shock with Hypochlorite & Muriatic Acid.

Concur with you about the alga as Clorine-consumption has been high for three-days.

Welcome to TFP!!

I'm wondering if you have a clogged impeller or suction line obstruction. Either of these would cause a low psi reading on your gauge, as could a clogged pump basket.

If it was the filter, your psi would rise, not get lower.

Thank you for the detailed posts