I just reviewed your post and note that you have a 700 gal pond. If
your pump turned it over every 2 hours, you would need only 350 gph
flow (plus some for pushing the water up to a fall or something for
the return. My guess is that you would do fine with a pump that
pushes 5-600 gph. If you are running a veggie filter (i.e. small pond
with plants) as a filter, you would want to take that additional
volume into account).

Again, others may have other wisdom for you.


Jim