[dacooltech]

cavitation and noise are both valid points

manufacturer assured me that cavitation won't be an issue with that 12V pump (which may become the AQX-100Z), in our application and its noise characteristics are similar to the AQX-50Z, but I have to try it myself before commenting on that.

well, actually this pump is like the AQX-50Z running @ 5500rpm

BTW the pump comes with 5/16" (8mm) connector on the pressure side, and 9/16" (14mm) on the suction side.

i also have another 24V pump that i received couple months ago with the following specs:
Connection Discharge x Suction Inch (mm) = 11/16" x 11/16" (18 x 18)
Max Flow: 4.2GPM (16 L/min)
Max Head: 27ft (8.2m)
Output x Input (W): 30x55

Size:
W: 4.41" (112mm)
H: 4.69" (119mm)
L: 4.65" (118mm)

now this one (equiavalent of the RD-20), which is also available in 12V, it cavitates when there's no good amount of restriction just as you already mentioned. So I can imagine how it's with the RD30 and 30RZ.

and I'll see about the AQX-100Z, once I receive the sample.