low pressure when adding DE.

Hi all. Last weekend I opened the pool. Unfortunately there was some mud washed in the pool form heavy rain so I started up the filter and pump and vacuumed up the bottom and back washed. Left the pump running all night and this morning the pressure was about 24 (with clean filter is between 12 and 15) so I back washed the filter and put in the DE. When I went back to the pump the pressure gauge was at around zero and the pump seemed to be struggling. Thinking that something might have clogged the filter, I back washed and removed the filter cleaned and installed back. I started the pump the pressure was at about 11. I added one scoop of DE and the pressure dropped to close to zero again. Any suggestions. The pump worked fine yesterday after starting and back flushing with no problem. Any advice will be greatly appreciated.
Amir

I would pull the top of the filter off and make sure mud and gunk is not blocking the intake where your pressure gage is.

Thanks. I did take the top off and cleaned the filter but did not check in take of the pressure gauge. However from what I remember the pressure gauge is screwed into the top half of the filter enclosure. I will check it out again tonight. What is puzzling is that it reads 10 psi before adding DE!
Regards
Amir

The impeller on my pump gets clogged with debris from time to time (a large volume of small stuff will pass through the basket but clump together at the impeller). Sometimes, I can pull it out with my fingers after removing the filter basket cover and filter basket. Other times, I need to remove the pump from the pump basket assembly and use a piece of wire to clean out the impeller channels.