The most important thing to take into consideration is the amount of water you want to move. For the health of the pond you need to change or cycle the entire pond every hour. This means if you have a 500 gallon pond you need a 500 gallon per hour (gph) pump to circulate the water. If you want to have a stream or waterfall this is not sufficient. A simple ratio to figure out the size of pump you need is: stream width x desired depth of the water in the stream x 50. For example, if I want an 18 inch wide stream, 2 inches deep the calculation looks like this: (18x2) x 50 = 1800 gph. This leads you to the next question. Which type of pump should I buy, an out of pond pump or an in pond or submersible pump? Do not buy a swimming pool pump or a Jacuzzi pump they are inefficient and will cost a lot of money to run.
Submersible pumps are the least
expensive to buy, but the most
expensive to run. A 3900 gph pump you
can buy at Home Depot will cost you
around $250 to buy. It will use about
700 watts of electricity. There are new
generation pumps that will use 175 watts
of electricity and pump 3900 gph - they
cost $350 and up. Inexpensive submersible pumps also clog easily since they have a built in screen to keep leaves and other junk out. More expensive pumps will not have the built in screen and can suck junk up to 1 inch in diameter through them. They do have advantages compared to centrifugal pumps in that they are quiet since they are in the water you will not hear them.
Centrifugal or out of pond pumps
start around $350, but they run on
less electricity and pump more
water. They last longer and have
fewer mechanical problems as well. These pumps will pump up to 10,000 gph. These type of pumps may produce a slight whining sound as they run, so keep them as far away from areas that have seating for pond enjoyment. Do not forget about running electricity to the pumps. It would be smart to run the wire in 1/2 inch PVC electrical conduit piping so later you do not accidentally cut into the wire and electrocute yourself. Place the GFCI outlet in a water resistant enclosure 3-6 feet from the pond and at least 1 foot above the ground. Check with your local city codes for exact requirements.
On average, plan on replacing the pump every 5 years if you are running it 24 hours/day all year.
Monthly cost of running a pump?
To calculate the cost of running the pump you would like to install use one of the following formulas: