I do have the 53257 in line temp sensor and did not know what port to use. Sounds like the high port as it has 4 wires?
Yes, it belongs on the high
Please note: The “Flow 2” connector may also be labeled as “aquabus low” on
the device. The function of this header is determined solely by the current firmware
version of the aquaero. Starting with firmware version “2010”, this header can be
connected to a flow sensor irrespective of connector labeling.
That's exactly what Shoggy says, it doesn't matter what it says, is is Flow 2.