Waterfalls and watercourses look great and bring the tranquil sound of running water into your garden. However, the amount of water flow can be difficult to calculate, so Andy Hobson explains how to work out exactly what's required.
There are some very good reasons for adding a waterfall to your pond. Water, breaking the surface of a pond adds vital oxygen, this is not only beneficial for ponds containing fish or other aquatic life but it has also been found to be very good at promoting friendly bacteria levels. This bacteria then breaks down sludge and silt which sits at the bottom of your pond and can pollute the water over time.
How Much Water Flow?
The trickiest part for most people is how much water flow is required. It’s actually very simple to calculate as I will explain.
First you need to measure the head height or head measurement, this is the height of the waterfall from the surface of the water, and then next measure the width of the waterfall.
If you want to achieve the type of effect that you see in most people's gardens, then the easiest way to calculate the flow is to measure the width in cm and multiply that number by 1.5, this will then give you the required flow rate in litres per minute (multiplying this amount by 60 will give you litres per hour).
It's important to have the correct flow rate as too little will just give you an unimpressive slow trickle of water, while too much will create an inappropriate torrent.
Waterfall Calculation Example
Here is an example of how to work out the flow required in litres per hour:
If your waterfall is 65cm wide: 65 x 1.5 = 97.5 litres per minute x 60 = 5850 litres per hour flow required.
If you wanted something slightly stronger then just double that number, but then we would advise higher walls to your waterfall to prevent water loss.
Of course, if you plan to have a tallish waterfall you will still require the same litres per hour but may need a larger pump that can achieve that height at the required rate. This is because as you increase the pumping height the output of the pump in litres per hour decreases.
Type of Pump
When possible, always use a solids handling pump as these can pump through a much larger pipe giving you less loss of pressure and a more consistent waterfall. Try to limit the joints and fittings you use as this can also cause a loss of flow.
If you are planning to have a massive waterfall or something with a very big drop it is advisable to speak with a pond specialist as they will be able to calculate an exact specification for you.
There will always be someone to answer queries regarding water flow on our 0121 355 7701 helpline or visit our aquatics superstore in Birmingham.