TLF Kalk Reactor

[Rogue951]

Hey anyone use this?
I've been underpowering it with the stock pump from the Osmolator and it's worked pretty well with the exception that it doesn't stir the kalk enough so it cakes.

Anyway finally went and bought a better pump for it.
I'm not sure if my check valve has failed or what but it's extremely restrictive and even straight up blowing into the valve it's barely putting anything through.
It's not mineral build up, it's only ever had RO water through it.
Anyone have any sugguestions?

It's one piece so I can't take it apart. Is there somewhere else I could by a 1/2" sized check valve?
I'm almost certain it's not supposed to be restrictive like this.
For comparison the airline sized check valve that comes with the normal ATO pump has a similar flow rate.