| The volume moved by a pump varies according to head pressure. The higher/longer the water is moved, the less the volume. Each pump differs. There should be a chart showing the volume your pump will move at particular heights, either among the papers that came with it, or available from the manufacturer/dealer. Check the manufacturer's website. Pumps sold for waterfall use are often high volume, low head, meaning that volume drops off quite a bit as water is moved much of a distance.
You are filtering 900 gallons, but it is in two connected ponds. My concern relates to the current velocity and having quiet areas for the fish to rest. I like to turnover the pond volume once every 40-60 minutes. More than that and I'd get concerned about the fish having to swim against current most/all of the time. But, in a large pond there are still quiet areas. If your pump moves just 1500 gph, you will be turning over each pond every 15-20 minutes. |