Should there be a seal between the sand filter standpipe and multiport valve? (Pentair TA60D)

[mungalo]

I bought a house with a pool last fall and ever since reopening it this spring, it's seemed like the filter is barely catching anything. The pump runs and moves water fine, but lots of debris (pollen, small leaves, etc.) comes back out the return ports into the pool (but no sand). The filter pressure is quite low too, usually around 12 psi.
I have a Pentair Tagelus TA60D sand filter. I opened it up today to find out why the water is bypassing the filter and there appears to be no seal between the valve assembly and the standpipe. It looks like the end of the stand pipe just butts up against the bottom of the valve assembly. The pipe ends are chamfered, but I have no idea if they're actually making a seal.
Is there supposed to be some sort of fitting between these parts to ensure a good seal? Is this likely the cause of my debris bypassing the filter?

 

[1poolman1]

No, there is no seal there. Chamfer is there to help the pipe and valve mate. Low pressure is a good thing. May need to add some sand if the filter is 5 or more years old. Try 50# of POOL SAND, it is a specific type for pool filters. Cover the pipe with a plastic cup and just pour it in. Do a quick backwash and rinse after adding the sand before placing valve in filter position. If debris continues to return to the pool you may neec a new spider gasket in the MPV.

 

[heikejohn]

Before adding more sand, make sure you don't overfill.
The sand level looks OK to me.