I have found that my Hayward never completely removes the DE when backwashed. Its a big unit, it takes 7.5 pounds of DE when you charge it. What I do when the pressure goes up is take the band clamp off and manuall hose it down to get all the DE out. Then I refill it with a full 7.5 pounds. I find that in 5-6 month season I only have to do this twice.