I'm eyeballing one of these, but I'm hesitant. I have a DDC pump top/150mm reservoir that I briefly plumbed with a return line into the bottom of the reservoir. The thing would never bleed properly though, because every time air bubbles came from the loop back into the reservoir, 80% of that air would just get sucked into the pump and pushed back into the loop. It looks like the XSPC Photon can only be plumbed bottom-return, unless you're willing to sacrifice the single top port (which I'm assuming can be used as a fill port?). How bad is it about re-ingesting air? I'd like to do a bottom-return so I can use a x-flow radiator and have a single low-point drain... but if the Photon sucks air like my DDC setup did, I'll skip it.