Sand filter "hydro dome" broken - do I need it?

[TexasDogs]

I opened up my (very old) sand filter (Baker hydro HRV-24) for the first time in a few months today and found this piece floating around. It's labelled "hydro dome" and I do see that part on some parts supply sites, but do I need it? I'm having a hard time comprehending what it's purpose is. For now, I just took it out so it's not jostling around causing more damage. Filter seems to work just fine without it...

 

[1poolman1]

If it works without it you should be fine. Without it in place the diffuser looks very much like a Pentair TR series diffuser that doesn't have a "hydro dome."