This is a good reservoir that looks great in a spare 5.25" bay. I especially loved how the DD logo is engraved into the face, BUT...
...the problem appears to be the difficulty or inability to totally remove the air from this reservoir, which becomes a problem when using the 1/2" fittings and more specifically, with a strong pump.
I am using the CPX-Pro Pump, and even on the lowest setting using a fan controller, there is turbulence in the reservoir that leads to bubbles being created that get sucked into the system. Part of the problem is the design of the frame around the fill-port. It allows air to get trapped around the edges and almost impossible to get them out.
As another user suggested and if you have the room, get the double-bay version or any of the others. I found that standing the reservoir on its face DOES allow you to remove all the air, but you need to completely bleed out your system before placing the reservoir back into place, otherwise, the bubbles come back.