I am installing the tubemeter in a Aquatube mounted in an AquaBay. The instructions state that best orientation is perpindicular to water level. If I install the resevoir correctly I can only mount the tubemeter ~30* to the water level. It appears to be located the same in the AC video.

Also the tubemeter is directly in the flow of return using a rear port is this ok? I am not sure if this will affect the performance.

No, if I line up the thumb tab of the res with the faceplate indent and use any of the rear ports it will be paralell with the water surface. So I am using one of the two side ports. It goes from lower left to upper right close to the sight glass to get clearance from the return and @ ~ 20* to the horizontal similar to the video AC has up on YouTube. Was not sure if I am using the ports most effeciently as they line up along the same plane with each other.

That or maybe I am not supposed to line up the thumb tab up with the face plate