When does a DE filter need to be disassembled for cleaning?

We've had our pool for a year now (yea!). For that entire time, the water has been crystal clear -- except the first month of pool ownership when I listened to a pool store tell me to lower my phosphates, and the stuff I poured in clouded my water (that was just before I found this forum!).

During that time, our DE filter has been flushed about six times or so (the first three times were within the first month of ownership, then a fourth time last August, a fifth time this past January, and I just flushed it for the sixth time today). The pool builder's pool start-up guy said that the DE filter should be disassembled and given a thorough cleaning at least once a year. I'm not willing to do that myself, so I'll pay a pool maintenance guy to do that for me.

Question: This forum is all about flaunting "conventional wisdom" and using tried-in-the-field practices for maintaining one's pool. What is the collective wisdom for knowing when you're really supposed to disassemble one's DE filter and manually clean the grids (either with a garden hose and/or soaking them in muriatic acid)?

Last August, when I backwashed the DE filter, the just-flushed, "clean" water pressure was 12lbs (with variable speed pump running @ 2750rpms). Then in January, I was surprised that the "clean" pressure was a little lower, just over 10lbs (same pump speed, same valve settings). Today, after backwashing, the clean water pressure is again 10lbs. So, I'm guessing that there isn't much old DE stuck to the filter grids, because each time I flush, I'm adding another 6lbs of DE powder through the skimmer.

Thoughts?

Famous,

Just like the pool guy told you, I have heard you should manually clean the grids at least once a season whether it is hosing them down or chemically cleaning them.

I just hosed my grids off for the first time a few days ago (bought a house with a pool over a month ago). I believe the timing of the cleaning depends on how your water is being filtered. What tipped me off was that I was having problems with small debris coming back out the returns. I received guidance on this forum I may have a multiport problem but checked the multiport and everything looked fine. Next, I opened the filter and found a dark substance caked on to the grids. All the grids were not evenly coated with DE so I knew I needed to just hose off the grids and start fresh. I am by no means the most handy guy but taking the grids out of the filter and hosing them was very easy. If you decide to do this yourself, don't forget to coat the ring with lubricant when you are putting the top back on the filter. I forgot the first time and I had a small leak.

Anyway, after cleaning the grids and re-coating with fresh DE, my filter has been operating 100% better than before I cleaned. I would say you should just pay attention to how your filter is operating.