Cloudy water on Spring start-up

My daughter bought a new house with a 16 by 35 inground pool. My calculations, it contains 25K gallons of water.

Equipment: Haywood, DE3630 Pro-Grid DE filter, with multi-port valve.

Pool was winterized by the local pool guys and re-opened just this week.

New DEX3600 filter was purchased and installed.

This Spring, they uncovered the pool and then dumped a couple SHOCK bags and some Algaecide. I should have saved the empty containers for reference. They also dumped 4.5 lbs of DE into the skimmer to charge it since it was new.

They reviewed with me how to use the multi-port valve and how to backwash the filter, and how to watch the gauge to determine when.

I have had to backwash and re-charge with DE at least 6 times in the first day. The water appears free of algae, but cloudy.

The pressure rises very quickly, I need to backwash/recharge in about 2 hours.

I am very new at this, never had to maintain a pool before.

I haven't seen any improvement in the cloudy water. How long should this take?

Please offer any suggestions, I should have paid more attention in Chemistry class.

TIA.