It's hard to say as I don't know anything about the Alpine pump, but for a smaller pond I like to
shoot for 1 1/2 to 2 times per hour turnover (6-8k/gph for 4000g pond) but you have to take into
account head loss of the bead filter and such too.
All filters have certain "speed" limits, or a max flow rate where they work best... s/g filters are 2000gph,
55g settling chambers are also about 2000gph, etc...
When figuring how the system is going to be designed, all those things need to be taken into account.
Knowing you want to flow, say 8000gph total, then figuring the best way of getting that amount of water
out of the pond, filtered, and back into the pond the best way possible, is the challenge.