I can't check on this now -- Hayward's website has crashed.

HOWEVER, in general, DE filters are plugged in minutes by live algae. To solve the problem, you need to kill the algae.

Also, I'm skeptical of your gallons figure: an EC-65 would be seriously undersized on a 28K gallon pool. It's very common for pool owners to have inflated estimates of their pool volumes, often because of misleading sales information. What are the actual DIMENSIONS of your pool?