I'll sell you a 5Gallon Bucket for $300!! (not Canadian though!!!,
it was an expensive bucket 
)...
Is there a formula you could use/make to work out flowrate in a closed loop compared to results from a 'fill your bucket' test?, or an educated guess of the percentage increase?(according to head?), cause the flow would be different when in a push/pull closedloop, than when in a push only one would'nt it?. the push/pull negates the head (or some?) does'nt it?...