Hayward manifold

[cisco61]

Hi everyone, I have a Hayward DE-4820 progress filter and yesterday I removed the top cover to rinse the filters and to my surprise, the top manifold was literally blown apart, it was crack in several places, I will load pictures as soon as I can.
The air releí valve is clean, not plugged, I have no clue as to what could've cause this.
Any ideas? Thank you in advance.

 

[mas985]

Welcome to the forum.

Water hammer comes to mind.

Do you have check valves in the plumbing and do they ever slam shut making a large bang?

What make/model pump do you have?

 

[chiefwej]

Opening or closing a valve, especially the backflush valve while the pump is running will do that.

 

[JamesW]

Blown out or crushed?

A high head pump can crush a manifold if the filter is dirty.

What was the filter pressure?

Maybe the water is flowing backwards?

Is the DE going inside the grids or outside?