Hi Fog,
I also have an EC-65 (thanks Waste for that great tip about leaving the plugs in!). What kind of pump do you have? Mine's a two year old 3/4 hp SuperPump and when my filter's freshly charged with DE it runs about 11psi. Bump time is around 20. Sounds like you may have a more powerful pump which might be why your working pressure's a bit higher.

When I first opened my pool, and was filtering lots of dead algae, I was bumping at least once an hour. I just kept at this until the water started to clear (36 hours or so) and then backwashed. Now that it's about clear I'll probably backwash once more which should hold me for most of the summer.

BTW, here's another tip: pick up one of those Hayward wands you connect to a hose and insert into the open drain of the tank. Do it whenever you backwash and you'll be amazed at what a normal backwash misses.