How To Test The Flow You Want For Your Waterfall

Here's a simple practical way to find out the flow that looks best for your stream or pond waterfall. Once you've worked out the flow then choosing the right submersible pond or waterfall pump is easy.

  1. Place a hosepipe into the stream or waterfall inlet. You ca adjust the water flowing through the hose pipe by selecting different tap positions

  2. Adjust the water flow using the tap until you are happy with the flowing water effect. Look for gentle interesting flow rates

  3. Without closing the hose fill a known volume container from the hose pipe. This could be a bucket of known volume or some other container. It's best if you get one for which you know the volume

  4. Calculate the flow rate by dividing the volume of the container by the time taken to fill it.

  5. This calculator would also allow you to weigh the container as an alternative to measuring the volume (if you know what a gallon or litre of water weighs (see below) then you can calculate volume easily).

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.

Rule of thumb for estimating water flow from pump for waterfall use

For every inch of pond waterfall lip width allow 250 litres per hour of pond water flow down the garden waterfall (this is about 50 gallons per hour - see table below here which provides you with examples).

Height of garden waterfall: do not make them too high. For most small garden ponds (up to say 500 litres or 120 gallons) garden waterfall 18 or 50cm above the pond surface is good enough.

Waterfall Pump Selection table

1. Vertical height of waterfall inlet above water surface of pond (NOT bottom of pond) ... measure this in feet. This is pond pump head

2. Width of water overflow point for waterfall ... if overflow is series of smaller overflows add all together to get width in inches. This is needed to work out waterfall pump flow required. The picture here shows what is meant by the overflow width ... take note at bottom of picture where you see water flowing over the edge of the last waterfall. This is the waterfall width you need to measure

Check where height meets width in the table. This is the flow your pump model must deliver. For a wide range of guaranteed Great range of low priced  pumps for small to medium sized ponds and waterfalls

  Waterfall Vertical Height measured from surface of pond ... (feet)
Width of Water
Overflow
(inches)

See image above

 

   1 ft 2 ft 3 ft 4 ft 5 ft 6 ft
3" 350 gph 500 gph 500 gph 500 gph 700 gph 700 gph
6" 700 gph 700 gph 700 gph 700 gph 1200 gph 1200 gph
9" 1200 gph 1200 gph 1200 gph 1200 gph 1200 gph 1200 gph
12" 1200 gph 1200 gph 1200 gph 1200 gph 1200 gph 1200 gph

Example ... you have a waterfall 3 feet above pond surface and overflow is 9 inches wide. You need a pump that will deliver 1200 gph at a height of 3 feet. An example of such a pump is  Danner Supreme Mag Drive 1200 gph as above.  If you have a waterfall 24 inches wide and 3 feet high you would need 2 model 1200gph pumps TIP: always go for one size larger if in any doubt ... Pumps for small to medium sized ponds and waterfalls