Phosban-reactor with Rowaphos question

[Delphinus]

Ok I put my Phosban reactor back online after not using it for a while. I had some Rowaphos still from before so I figured I'd use it up before buying new.

To start off the reactor I went with half the recommended dosage just to prevent phosphate shock like they say is possible with the Rowaphos since it strips phosphate too quickly (or something like that). So there is currently 60ml of Rowaphos in the reactor (tank system is about 110gallons total water volume).

I have the flow through rate cranked back to a tiny trickle. The flow control valve is almost all the way closed.

My tank is testing at 0.25ppm PO4. The output of the phosban reactor is also testing 0.25ppm PO4.

What do you make of this? Flowrate too high? (If so, what are people setting their flowrates to on these things?) Or is the Rowaphos spent? Should I try upping it to the full-strength?