DE Blowback in returns

[nofrontwheelcatwalk]

Dad’s pool is blowing DE back, grids were pretty worn and old so I replaced em and it continued, looked over the manifold and it had no cracks and I double check I seated in all the way down all the way around the honeycomb. Replaced the multiport and gaskets for multiport still doing the same thing. Only thing I can think is the inlet oring is deceptively worn but it looks great.

 

[PoolStored]

What brand and model. When rebuilding, always a good idea to replace o-rings and triple inspect all parts and grids.

 

[HermanTX]

looked over the manifold and it had no cracks and I double check I seated in all the way down all the way around the honeycomb.

The manifold can be deceptive. It may be a hairline crack that opens under pressure.
Ensure to lube all orings.
Post a picture of the complete manifold.