If you're shopping for a waterfall pump, learn how to measure flow rate first

Just as the primary pump in your garden pond has a desired flow rate, so does a pump for your waterfall. In basic terms, the amount of water flowing over the waterfall is dependent on the width of the overflow lip or edge.

The wider your waterfall lip, then obviously a higher amount of water will need to be provided from your pump. But if you just want a trickle of water, there's no need to have a wide lip or overflow. The rule of thumb here is 250 gallons of water per hour per inch of overflow edge.

For example, if you have a waterfall with an overflow lip that's 6 inches wide, then you'll need a pump that will deliver the following volume of water: 6 x 250 = 1,500 gallons of water per hour.

Now if you already have a waterfall pump installed, and you're not happy with the amount of water flowing over the edge of your waterfall, you have several options:

• You can reduce the width of your waterfall overflow by placing stones or large pebbles across it, thus requiring less water volume to product an attractive waterfall.

• You can run two pumps in your pond system instead of one, and use the smaller pump to operate your biofilter. Click here to read article about using 2 pumps to save money in your garden pond

• Make sure the tubes leading up to your waterfall are as short as possible, and if they're narrow, replace them with larger diameter tubing.

Here's a good trick for determining how much water you'll need for your waterfall, and how much water looks good spilling out of the overflow:

• Place a hose in the waterfall inlet

• Adjust the water flow until you're happy with the result

• Now, without shutting off the water, take the hose and fill a known volume container while timing how long it takes to fill.

• You can determine the flow rate by dividing the volume of the container by the time taken to fill it

• If you're not sure how much water the container holds, you can weigh it to find out. 1 US gallon of water weighs 8.83 pounds (minus the weight of the container, of course). 1 liter of water weighs 2.2 pounds.

  For more on waterfall pumps read this article.

Our Partners

• USA: Macarthur Water Gardens
• UK: Bradshaws Direct
• South Africa: Super Pumps

Fish Ponds