SIZING UP A POND PUMP – PART THREE – How To Select The Right Pond Pump For Your Backyard Pond

Welcome to the third and final part of our sizing up a pond pump mini series. In this episode we’re looking at how the pond hose you choose can affect your flow rate.

If you haven’t looked at Part One (the basics of sizing your pond pump) and Part Two (how the height you want to pump to affects your pump performance) go back and check those out first.

Then watch the video below for the final piece of the puzzle:

SIZING UP A POND PUMP – PART THREE – How To Select The Right Pond Pump For Your Backyard Pond – Transcript

Sizing Up A Pond Pump

Part Three

G’day this is Scotty Tucker,

The second stage for sizing up a pond pump is when we come back to that information about when you pump up to a height you lose your flow, the other thing that influences your flow with a pond pump, is the size of the hose.

Both in the diameter it is that you’re pumping into and also the length that you’re pumping to.

And that covers, it’s an aspect called friction loss.

So when you get a pump and you try and pump water and you push it through a hose, what happens is that as the water travels through the hose, it grabs up against the side, it becomes a little bit turbulent inside that hose.

So it slows the water down.

It doesn’t flow through super fast or as fast as what it does without the hose on it at the end of the pump because the hose slows it down a little bit.

Now, the thing with pond pumps is that they are different than other types of pumps.

If you’ve got a swimming pool pump for example, those pumps use a lot of power, they can move a fair bit of water, but more importantly they can move that water through relatively small diameter hose and long lengths of hose.

That’s because what they’re designed to do, they’re designed to go around corners and all sorts of angles in swimming pools, and up pipes and pump up to solar systems on roofs and all this type of thing.

And that’s one of the reasons why swimming pool pumps are very power hungry and you should never use them in a pond because they’re not made for ponds and you’ll get your first power bill and go holy crap, this is costing me a fortune to run.

With pond pumps it’s different, they go the other way, they move a lot of water, but they don’t have much pressure behind them.

Which means that they don’t use much power.

That also means that they’re not designed to push water through long distances of hose or small diameter hose.

So for example, coming back to that four thousand litre an hour pond pump.

For a four thousand litre an hour pond pump, you might get away with 25mm diameter hose, but you’d be better off using 32mm diameter hose.

Because that difference between 25 and 32, although it’s quite small, and sometimes even when you’re looking at the hose, with the naked eye you can barely tell the difference, but the difference that you’ll get on how much water you get at the other end is significant.

So what can happen is that if you do the right thing and pick the right size pump, but then put it through very small hose, you’re not gonna get the flow that you expected out the other end.

And you’re gonna then have to step up to a larger pump just to try and get the water flow that you want coming out of your fountain or your waterfall or whatever it is.

So selecting the right diameter hose is critical because it can save you hundreds of dollars between having to increase the size your pump.

Very, very important, when you start running into situations where you’re building a new pond, lets say it’s a concrete pond, and you get someone who’s not really an expert in pond design, and this type of information, what we see time and time again is unfortunately we’ll see clients that might come into us and say right, I’ve got a ten thousand litre pond and I wanna pump it up a two metre high waterfall and have Niagara falls and its all been built and constructed and we’ve got 19mm pipe.

That means you are screwed.

It means that you’re gonna have to use a pool pump just to try and get that flow which means that you’re gonna have to be paying an enormous amount in power bills.

So it’s super important to get the hose diameter right.

Again coming back to the general rules of thumb, you don’t really want to be using half inch hose or 12/13mm hose on any sized pond pump.

It’s just not really something that you’d want to use.

You might use it on a tiny little matchbox size pump if you’re just pumping through a little ornament frog spitter or something like that, that’s about it.

When you sort of start getting into the thousand litre, to a couple of thousand litre pond pump ranges, you might use a three quarter inch or a 19mm hose.

When you start getting to say two thousand to four thousand you might get away with a 25mm or a one inch hose.

Four thousand to six thousand maybe a 32 or a inch and quarter hose.

When you start getting sort of eight thousand and above you’d go to 40mm.

When I say above you’d probably switch to 50mm at about say maybe fifteen thousand litres there abouts.

When you start getting into twenty thousand, thirty thousand, forty thousand and beyond, you may use 50, you may also then jump up to say a 63 or a 65 or even an 80mm

When you start getting into those larger pond pumps and those larger sizes, you’re far better off to speak to a pond pro before you go and do anything.

But for your average sort of backyard pond, you’re generally gonna be using hose size of about 32 to 50mm depending on how long you’ve gotta run that hose for and the height that you’re pumping it up to.

So get your pond volume, figure out the pump, factor in the hose size that you’re gonna be doing as well, are there’s your starting point for choosing the right pond pump.


If you’ve gotten this far and you’re still a bit confused, don’t worry, it’s a delicate process and our friendly expert team are happy to help you work out what size pond pump you need. Simply fill out a contact form or call us on 1300 005 670 for assistance.