Sand Filter Pressure Problems; Sand Bad in 3 MONTHS of USE?

[CarlD]

950 # of sand????? are you sure? I have a 20" filter and it uses 200#.

Update: I checked Pentair's web site and a 36" does take 925 # of sand--and is appropriate for a pool with between 67,000 and 101,000 gallons! The BIGGEST home pools here we see are in the 40's... Is your pool that big?

Saying that, I'll bet ANYTHING your multivalve is bad, not your sand. It's POSSIBLE the laterals in the filter have broken as well. If you don't get a release when you push down, something is definitely wrong.

So, from what I can glean sand is not likely your problem. Something else is.

[Poconos]

When you push down on the handle that opens all ports and you probably got the drainback from air coming into the waste port. Since it now does not drain down, what do you have on the waste line? If you have one of those thin drain hoses it could simply collapse under suction and block air flow into the waste port. Thus no drain down. A stupid question and one that seems unbelievable, is it the right type of sand? Sounds like this pressure issue happened over some short period of time but not immediately. Wrong sand could slowly plug the laterals which are nothing more than pipes with slits. Also hard to understand any failure mechanism in the valve that would cause this problem. I think that filter has side mounted ports and I don't know about the internal plumbing of those things. Is it possible sand somehow got into one of the wrong internal pipes and is blocking flow? Just some thoughts.
Al