Dlophin 7500 -vs- Hammerhead 5800 for closed loop?

[sarmo]

i have a 500 gallon display that is 8' x 3' x 3'. the tank was never drilled for a closed loop so i have done all the plumbing over the top.

my question is which pump will give me the best results?

i have both pumps currently so cost is not an issue. of course i want to maximize flow and i'd like to increase the pressure coming out of each of the loc-line outlets.

here is a drawing of what i have.

View attachment 500 Display.xls

thanks for looking