2xD5 vs 2xDDC long loop comparison (serial scaling)

[Waterlogged]

Waterlogged: IIRC dual pumps in serial = double head pressure, in parallel = double flow. DDCs have loads of head but less flow, who knows, maybe might show more flow that way .. but somehow it seems that you'll loose redundancy that way (as in if one DDC stops, big part of flow might go through failed pump subloop because it seems to be way of least resistance, instead of going all the way through loop with many resistive waterblocks. Should be easily workarroundable though by putting ball valve there to switch off that failed pump subloop though.

Exactly, it would double the flow of the DDC's. They are already strong enough to keep the water flowing through the loop on their own so putting them in parallel should kick them into overdrive on the flow rate. As for redundancy, in either case (serial or parallel), there would still be 1 pump running in the loop which should provide more than enough to keep it running until a safe shut down can be initiated.

A good parallel setup for Luke would be something like this (not sure what his current order is, I went off older pics in his log to determine this order).