Water Gardening: Advice on Pumps for Pond, 1 by CT_Ohio

CT_Ohio wrote:
Thanx Guys: I've attached a picture of the pond in progress. Lower pool is 4'x5'x3' deep and upper is 4'x2'x4' deep. Waterfall height is 3'4" from bottom of pool and 26" wide at front edge (20" where it goes through wall). All told about 675 gallons for both pools. I've read water should be exchanged every 2 hours (~350 GPH pump) but online pond suppliers say once every hour (675 GPH pump). Also read that for waterfalls every lateral inch of waterfall requires 125 GPH of pump (2500-3250 GPH pump. Needless to say, all this conflicting info is very confusing. I want a pump big enough to supply the waterfall but not so big that it disturbs any fish or plants. Help a poor lost newbie!