Poor Suction

I have a 12,000 gallon pool with a Hayward DE pump. I am not sure of the manufacturer of the motor. We have a suction based cleaner that we run daily. We have an automated chlorinator. My son takes care of the pool and swears that the suction has decreased substantially over the past year. He says he has to backwash the pump about every two weeks to increase suction. Any advice on other sources for loss of suction would be appreciated.

Thanks for allowing me aboard!

Do you mean a DE *filter* plus a Hayward pump?

Have you disassembled the filter completely and cleaned it this year?