Perhaps you are in the planning stages to create your Koi pond, or it is already set up to hold water. Now is the time to decide which traffic gear to buy. Suddenly you are faced with a dizzying array of pump and filter options! Don’t feel overwhelmed! Asking a few relevant questions and applying a few guidelines can help you select the right equipment for your pond’s needs.
traffic requirements: Assuming there are any fish present, it is generally accepted that the entire pond should be circulated at least once every two hours. It’s even better to do this every hour, especially if you have a lot of fish. For a 2,500 gallon pond, you’ll want a pump that moves 1,250-2,500 gph (gallons per hour). If you plan on having a waterfall more than a few feet high, additional power (and gph) will be required. See pump gph rating with head (head).
What is the volume of the pond?? You can already see why it is essential to know the volume of your pond. Determine the gph capacity of the pump you will need.
To calculate the approximate volume, apply the following rules.
For a square or rectangular pond: (Width in feet) X (Length in feet) X (Average Depth in feet) = Volume in cubic feet.
For a round pond: (Radius or half-diameter in feet) X (Radius or half-diameter in feet) X (3.14) X (Average Depth in feet) = Volume in cubic feet.
Divide your pond into several sections if it has an irregular shape. Once you have the volume in cubic feet, multiply by 7.5 to find the gallons of water. This is because 1 cubic foot of volume contains 7.5 gallons of water.
Example: A rectangular pond –
(16 ft. long) X (8 ft. wide) X (3 ft. average depth) X (7.5 gal/cu. ft.) = 2,880 gallons.
Circulating the pond every 2 hours requires a pump rated at around 1500 gph. Hourly traffic dictates around 3,000 gph. Remember that a waterfall increases the requirement, as does a large fish population or lots of sunlight. For this pond example I would recommend a 3000 gph pump.
Submersible or external pump? Submersible pumps are fine for smaller volume ponds. They are underwater, out of sight and silent. They are also less expensive than external pumps. To clean a submersible pump, you pull it out of the pond with the hoses still attached. An external pump still has an inlet (into the pond), but an occasional cleanup of that inlet is easier than a submersible.
The main advantage of external pumps is that they are much more efficient. Look at the amperage the pump draws; is directly related to your electricity bill. A 4,000 gph submersible pump may draw 10 amps, while a 4,000 gph external pump may draw less than 3 amps. That’s a big difference, especially over time.
Generally speaking, a submersible pump up to 3,000 gph is a good choice. When you get to 4,000 gph and beyond, the external pump is clearly a better choice due to its efficiency.
Biological Filter: This part is quite easy. Filters are clearly rated for gph capacity, and now you can simply match that to the requirements of your pond and the pump you’ve chosen. Most good filters combine mechanical filtration with biological filtration. Biological filtration is an absolute must with fish. Definitely select one with an easy backwash feature! There are various media options, and pearl filters are quite popular now.
You will need to measure the amount of flexible hose required to connect your equipment and run to the pond and to a waterfall; allow extra. Ask your dealer if you are sure which diameter hose to use with your pump.
Those are the basics you’ll need to consider when choosing the right circulation equipment for your pond. Now you should be able to enjoy your healthy fish!
