Reef oct biopellet 110 help please

[Alwmh4]

So I was cleaning my biopellet reactor and got everything put back in place, so I thought, then found this piece that didn't make it back in. Anyone know where it goes? I can't find any detailed parts list for coral vue and the paperwork that came with it is minimal

Any help would be appreciated.

 

[Downbeach]

http://www.coralvue.com/biopellet-reactor-down-pipe-with-check-valve

 

[Alwmh4]

I'm not seeing where this part is. Is it inside down pipe?

When I took this thing about I had no idea there were pieces inside to keep track of

 

[Downbeach]

Yes, its a check valve inside the down pipe.

From the linked article:

 

[Alwmh4]

Hmm ok well I tried to put it back like picture and no water can pass now. Makes me think another part is missing

 

[Jsieger89]

If no water is passing now try turning it around