FNS Plus blowback

[Veryexpensivepools]

New grids, new manifold, new inlet pipe o ring, new backwash valve. Still blowback? Gasket at outlet pipe to filter wall? Black inlet pipe? White outlet pipe?

 

[Poolbreh]

Is this a Pentair fns plus or does it pre-date?

 

[Veryexpensivepools]

Is this a Pentair fns plus or does it pre-date?

Plus

 

[Poolbreh]

One of the grids may not be seated properly in the manifold, if the split connector on the grid is exposed it will pass.

 

[Veryexpensivepools]

One of the grids may not be seated properly in the manifold, if the split connector on the grid is exposed it will pass.

I checked that. What about possible hole in new grid? Besides these things, anything else? The blowback is immediate from dropping DE in skimmer.