Bitspower D5 MOD TOP (Black "S" Model)

@Xerxes please provide link or more info about this acrylic anti-air chamber plug? I have had this top for some time & with different setups I have always wondered why my flow rate is quite low?

Resurrecting this thread since there is no clear answer for future inquirers. That acrylic plug piece prevents the giant bubble from forming on the unused water pathway. I don't think it's a huge problem if you don't have it but a giant bubble could slow down pressure a tiny bit because when the pump puts pressure on the water in the pipes/radiators some of the pressure escapes to that bubble squishing it a bit instead of pushing the water through.

Oh, no, that piece comes with the Bitspower Dual / Single D5 Top Upgrade Kit; not with the D5 top. It plugs one of the G1/4 ports on the front of the pump, which becomes the top when the reservoir is mounted over it.

No, the acrylic anti-air chamber is a small (about 6mm x 14mm) acrylic plug that screws into a hole inside one of the openings in the D5 Mod Top. Bitspower sells kits of various sizes, but I can't find anything that explains their purpose.

I'm sorry; I don't understand the question. Not sure what you mean by 'anti-air chamber'. Are you asking about installing a reservoir on it? If so, it can work without a res attached just fine.