Pentair Rainb #300 off-line chlorine feeder check valve

[fwoz]

I recently installed this feeder. The installation instructions say I should also install an optional R172323 check valve on the inlet side.
My installation taps in just before de filter with outlet downstrean of heater check valve.

Do I need the "optional" R172323.

Thanks

 

[Bama Rambler]

While I can't say if you Need the check valve it's just good practice to install one when there is a possibility of any backflow. If it were me, I'd install it.