How to Measure The Water Fall Flow Rate So You Can Choose Right Waterfall Pumps

You need a pond and waterfall pump that gives you the desired flow to suit your needs.

In simple terms the amount of water you would like to see flowing over a waterfall is dependent upon the width of the overflow lip or edge. If you have a wide waterfall lip then obviously you would need a larger amount of water from the pump to flow over the edge. The picture below shows a nicely balanced height and flow distribution of water over the waterfall into the pond ...

In the picture here you'll see a waterfall with a single lip. The width of this lip is 10 inches and the water flow is about 3,000 litres per hour (790 US gallons per hour or 940 Imperial gallons per hour). The waterfall inlet is 35 cm (15 inches) above the pond surface. Notice the degree of aeration where the water cascades onto the pond surface.

If the water flow was a trickle then there would be little point in having such a wide overflow. The rule of thumb is 250 litres to 350 litres per hour of water per inch of overflow edge (about 65 to 95 US gallons per hour).

Here's how you find out how much water you need to pump using another method...

If you would like to test how much water looks best for your waterfall do the following ...

• Place a hosepipe into the waterfall inlet

• Adjust the flow until you are happy with the effect

• Without closing the hose fill a known volume container from the hose pipe

• Calculate the flow rate by dividing the volume of the container by the time taken to fill it. This week's free calculator could come in useful here.

This calculator would also allow you to weigh the container as an alternative to knowing its volume. For water use the following:

• 1 US gallon weighs 8.83 lbs

• 1 Imperial gallon weighs 10 lbs

• 1 litre weighs 2.2 lbs

If one hose does not deliver sufficient water then use 2 hose pipes.

How To Convert Different Measurement Units

• To convert gallons to litres multiply by 4.54

• To convert gallons to US gallons multiply by 1.2

• To convert US gallons to litres multiply by 3.78

• To convert cu.feet to gallons multiply by 6.23

• To convert cu.feet to US gallons multiply by 7.48

• To convert inches to cm multiply by 2.54

• To convert feet to metres multiply by 0.305

• To convert pounds to kilograms multiply by 2.2

• To convert sq. feet to sq. Metres multiply by 0.093

• To convert cu metres to litres multiply by 1000

Of course to convert in the other direction you divide by the factor. For example to convert litres to gallons you would divide by 4.54

Importance of PIPE DIAMETER and PIPE LENGTH for a pond ... Hopefully you have decided to download the free calculator from Free pond calculator page By inserting different values for length and diameter you will see amazing impacts upon pump specification. You might find it difficult to believe but using small diameter pipes (especially long lengths) can reduce your pump flow to a trickle. Pipe diameter has a bigger impact than pipe length in most cases. Always use the biggest diameter pipe you can and always have the shortest length. Pumps and pumping systems are the source of live-giving oxygen to your fish and plants as well as your biofilter's bacteria.