My bad.
My water intake from the ro/di tank is on the intake side of the PH on the
kalk reactor, so there is "one" hole out to the sump. But I have several holes in the "cylinder" part. If this helps.
Sounds like your kalk reactor is the same design as mine. Got a pix?
My kalk reactor is a diy out of 4" acrylic tube about 20-22" tall, two piece and the intake for the pump takes the water from near the top and forces it down to near the bottom. With a maxi=jet 900, it stirs up the kalk really good to almost the top of the tube. It's called a recirculating reactor.
Not had any pressure related problems with the two PH's.
hth