I don't own a power adjust, but as far as I'm aware they are really just extensions of the Aquaero 5. I doubt a flow meter would work without the aquaero, there is nothing to do the processing.
A power adjust by itself, combined with the Aquasuite software might give you manual control of the pump but that is all.
You can run a Flow meter from the PA2 along with a Pump (or fans..As the same power output is used for Fans or a Pump) & using the 2013 Aquasuite Software no problem..
You don't need to have a Main Aquaero 5 unit to run or monitor the PA2 flow meter or pump..
If your running a pump from the PA2 then you can't attach any fans & so it's the same sort of thing the other way round, If your running fans off the PA then you can't run a pump at the same time, But you could still use a flow meter as well if a Pump or fans are connected at same time.. either way, doing this means you don't have to have a main Aquaero 5 unit..
What it comes down too is, Your more limited as to what & how much you can attach to each PA with running just two Pa's..... If your going to be wanting to run a few fans as well then I would suggest your going to need an aditional Aquaero 5 main unit... but thats just my opinion & what I would do
N.