Low pressure in filter?

Here's a new one for me -- suddenly the pressure in my DE filter has dropped, pretty dramatically.

It is always around 40psi (and when it gets dirty it goes to 50 and I know it's time to clean) but today I looked and it went to 20psi. The rest of the system seems to be functioning fine (although my salt chorinator says "low amps" but I suspect this is a separate issue) and I have no idea how to or even if I should fix this (cleaning the filter wouldn't make the pressure go up, right?).

Any ideas? Or should I not worry?

suction side restrictions will cause your filter pressure to decrease. Check your valve positions and make sure your skimmer and pump baskets are not clogged.

40 psi is pretty high for a clean filter pressure. Do you have infloor pop up cleaning system?

Low Amps on your SWG:
1) check your cell for scale
2) check your cell cord for damage of loose connection
3) verify your salt level is where it needs to be
4) how old is your cell? May be wearing out.

Well, it's always been that high on the filter so I don't know. Skimmer basket is fine (and good suction) but I'll check the pump basket (all valves seem to be operating correctly).

I think the problem with the cell was that it was clogged -- I cleaned it and I suspect it will be fine (only a year old). Salt level is fine (but zero Stabilizer so I'm having issues with it holding chlorine, natch -- will take care of all today).

Thanks as always for the help.

Oh, and yes we have an in-floor cleaning system, if that makes any difference (does that account for the higher pressure?)

You'd have to have a high-head filter to get anything close to 50psi. Mine only goes to 36psi with the returns plugged. Don't ask how I know that.:o I bet you have gauge problems.

John is right. Way too high and probably impossible to reach with a regular impeller type pump. My 1 HP superpump can only hit around 30 with blocked flow. At least with the Hayward sand filter tanks, they are only rated to 50 psi. Really sounds like a messed up gauge for starters.
Al

Well, it's a 2 1/2 HP pump, and the pool guy which set it up seemed to think the pressure was okay but even assuming for a minute the gauge itself is inaccurate it wouldn't negate the fact that it suddenly read about half of what it read previous.

I haven't checked the basket yet (will tomorrow morning -- was too busy tonight) but otherwise I'm not sure what could be going on. Everything else (infloor cleaning, skimmer, spa) seems to be working fine.

If the pool guy thinks 40 psi is OK then I'd change pool guys. The system isn't sized properly. Could be small piping, small filter, way oversized pump, or anything in the return side that is limiting the flow. I don't know anything about DE filters other than what I've learned from this forum but if we assume the filter is the restriction causing high pressure what if a grid broke and you're just bypassing the filter media? Also, what about the pressure during backwash. Did that change?
Al

This system is *exactly* the same as three others in this development (including initial pressure readings) so for the moment I'll assume it was set up properly and either folks here don't have experience with this kind of system (and therefore can't help me) or just don't get it.

Since nothing else is working incorrectly except for the gauge pressure drop I guess I'm not going to worry about this further. But thanks for the replies.