There are many factors to consider when choosing a pond pump. Some of those factors include:
Benefits to having a submersible pond pump is that it can be concealed and out of view by placing it in the pond. It also can eliminate any noise by having it submersed in the water. A 'downfall' of having a submersible pond pump is that if you want to unclog it or remove it for the winter, you have to get in the pond in order to remove it. A neat idea, though, may be to tie some black nylon rope on it's handle (if applicable and not too heavy) and conceal the nylon rope (which will float). When it's time to remove the pump, you may be able to grab on to the nylon rope and pull it up.
Benefits to having a centrifugal or out-of-pond pump (non-submersible) is that it's easier to maintain by eliminating the need to get into the pond to access it. They can be a bit noisy though, depending on the size, which may be muffled or eliminated by placing a fake rock cover with air vents over it. Centrifugal pumps are designed to push water, not pull it, so they should be located at water level near the pond's edge and then push the water up to a waterfall or nearby water feature.
Centrifugal pumps or submersible pond pumps can also be used as irrigation pumps. Many people who have a pond on their property set up their pump by pumping the water from the pond and using it for irrigation purposes. Either a centrifugal pump or submersible pump can be used for irrigation.
Determining the Size of Pond Pump You Need
After you've determined whether you want a submersible or centrifugal pump and the voltage you have available, you will then need to decide what size of pump your water feature needs. To calculate the size, there's a little math involved and a few measurements you will need to get.
In order to calculate the size of pump you need just for a specific water feature (and NOT to provide overall pond circulation), then here's some steps will need to take:
1. Measure the width of your water feature, such as a waterfall. The width of the weir is what you need and the weir is the top of the waterfall area where the water first drops or 'falls'. Measure this in inches. Write the number of inches down. As an example, say your waterfall is going to be 24" wide.
2. Measure the horizontal distance from where the pond pump would be located to the waterfall. As an example, say your waterfall is going to be 25 horizontal feet away from your pump. You pond that you're going to make is going to be 15' long and you'll put the pump at the opposite end of the pond as the waterfall which will be 10' away from the pond's edge. Add up 15' + 10' and you get a total of 25 horizontal feet.
3. Now, measure the height the waterfall will be from the surface of the pond water. Note, I said surface of the water. For our example, the height of the waterfall will be 3' high - or 3' higher than the water's surface.
4. Now, here's where we plug in our numbers and do a little math. Don't worry, it's pretty easy. For every 10' horizontal distance the pump is going to push water, you consider it as a 1' LIFT. I know you haven't heard of 'lift' yet, but just write it down for right now. In this case, our pump was going to be located 25 horizontal feet away from the waterfall. Divide 25 feet by 10 and you get 2.5' of LIFT. Write that number down.
5. For every 1' of vertical height the pump is going to pump water, you add 1' lift. In our case, the pump was going to pump 3' high. So, 3' divided by 1' and we get 3. This number is also part of our 'lift'.
6. Add the horizontal lift (which was 2.5') and our vertical lift (3') and you get 5.5' of lift. Write this down and circle it. Put it in bold. It's very important.
7. Now, in regards to the actual waterfall itself.... You want to create a waterfall that is 24" wide, right? (Wink, wink! Of course you do! :o) Or at least, that's our example any way!) Here's our little math for this part of the equation. It's even easier than the lifts, so don't worry! Here it is: For every inch wide the waterfall weir is, you multiply this number by 100 GPH. So, since our waterfall weir is going to be 24" wide, we multiply 24" x 100 GPH and we get 2400 GPH. Write this number down. Circle it. Put it in bold. It's part of what you need.
8. Now, we'll put it altogether! You need a pump that will pump 2400 GPH at a 5.5' lift. Let me tell you this... This is NOT a 2400 GPH pump! This is a pump that will pump 2400 GPH at a 5.5' LIFT! Let me explain...
Manufacturers of pumps will include performance charts for their pumps. This performance chart indicates how many GPH (gallons per hour) that particular pump will push water at a certain 'lift'. Typically, the LABEL ON THE PUMP INDICATES A 0' OR 1' LIFT. You will have to read the performance chart for your specific pump to make sure it can pump 2400 GPH at a 5.5' lift. This size of pump may be labeled as a 2850 GPH or some other number because the pump 'may' push 2850 GPH at 0' or 1' lift but by the time it pushes the water at a 5.5' lift, the amount of water pressure is less... The lower pressure available at 5.5' lift may be just what you need - or it may be too much or too little. So, you will have to check the performance chart for each pump and DO NOT refer to the label of the pump as this is typically labeled at a 0' or 1' lift - NOT the lift you need!
I tell you all of this because it's VERY important no matter if you're looking for a submersible pump, centrifugal pump or irrigation pump. There is a little math you need to do in order to determine the right size of pump for your application. What happens if you don't do the math? Your pump is too small for your pond... or your pump may be too larger for your filter or waterfall and it pushes water everywhere. You get the picture...
For larger pumps required for large water features, the performance chart can show a dramatic change for just a few feet so be sure to do your math and measure everything, too.
Also, in regards to large pond pumps including centrifugal or submersible pumps, many people think that you need a certain HP or horsepower to provide the flow you want. This is NOT true! Manufacturers have continued to make their pumps more energy efficient and many pumps on the market today require less energy they did years ago while providing the same or more pressure. So, don't go by horsepower. Some are also designed to provide a whole lot of pressure but not for a long distance while other pumps are designed to go a long distance but not with a lot of volume. All the pumps are different. Bottom line: Check the performance charts for any size of pump. Pumps are non-returnable too, so you want to make sure you've calculated the size you need correctly.
Well, I hope this helps. We have a huge variety of pond pumps including submersible pumps, waterfall pumps, centrifugal pumps, irrigation pumps, etc. If you need help in determining what size of pond pump or centrifugal pump you need, don't hesitate to ask. Simply email us with your measurements and we'll be happy to help!
Once you have chose the right size of pump you want, then you'll be able to determine what size of tubing you will need to do your plumbing as the intake and discharge size of the pump is the size of tubing you will need for your application.
For those requiring more specific information including pipe friction loss, industrial pumps, etc., please contact us with information for your application.