Waterfall pump calculator or Stream Calculator

Our waterfall pump calculator and stream pump calculator will help you determine the size of the pump required to power a waterfall or stream.

As the width of the falls or stream increases, the GPH that flow over the spillway or flows down the stream will also increase.

If the spillway width or stream width increases and the GPH does not increase, the sheet of water or flow of water will become thinner and thinner, not producing the desired effect.

Turn over rate.

It is best to turn the volume of water that your pond holds through your filters every hour.

This may be impractical for larger ponds so try to achieve a turn over rate of at least every 2 hours.

If the pump required to achieve this exceeds the results of the below calculations that the waterfall pump calculator gives you, go with the pump size that will give you a good turn over rate.

If you find that you need a pump that is to powerful for your waterfalls or stream to look correctly, simply divert the excess flow of water, after the filters through a return pipe back into your pond. This is particularly useful if you have an area of the pond that has poor water circulation.

125 GPH is the accepted minimum for a waterfall.

Here is why this works well.

125 GPH will produce an sheet of water over the weir, even if the weir is slightly out of level.
If the weir is not level and you go with less then 125 GPH you may end up with dry spots on the weir.
Will produce the sound and look of a waterfall and not the sound of multiple drips.

The chart below will give you a good idea of what to expect if you increase the GPH.

GPH = Water Thickness (Over The Weir)

125 = 5/8"   140 = 3/4"   186 = 1"

252 = 1-1/4"    324 = 1-1/2"   405 = 1-3/4"

150 to 180 GPH is the accepted minimum for a stream.

Some tips on streams.

Streams act as biological filters so like any biological filter the longer it takes for the water to flow through the stream the better it will act as a filter.
Create some wider areas or even vary small/shallow pond areas to slow the water down and plant bog plants in this area.
Create narrower areas to increase the flow of water.
Don't place to many rocks in narrow areas. This may act as a dam and cause the stream to overflow.
Step 1

Please enter all numbers into this waterfall pump calculator as directed by the text next to each box.

Spillway Width Or Stream Width (In Inches)
Number Of GPH (See Chart On The Right)

Total GPH of pump required at 1 or 2 feet in height (see step 2)
Step 2 (optional)

The numbers above define the GPH required to power your waterfall or stream, but now you have to pump that water up to the falls or stream.

There are fittings, filters, and pipe that the water must pass through and this will effect the performance of your pump. So enter your numbers below to find the true height factoring in the resistance.

Vertical Height (In Feet and decimals of feet, example 3 1/2 ft=3.5)
(Measured From Water Surface, To Top Of Waterfall Or Top Of Stream)

Number Of 90° Bends, Reducers
Tubing Length (In Feet and decimals of feet)
Number Of Adapters Or Fittings

Total Vertical Height (Dynamic Head Pressure)

Due to resistance in pips, fittings, and gravity the performance of your pump will decrease.
The number above equals the total hight the pump is expected to pump to. (height + resistance)

Now that you have the results of the two calculations from the waterfall pump calculator above you are properly prepared to make right pump choice.

There is only one more piece of information needed.

You need to know the pumps performance under a load, otherwise called a flow chart.

All manufacturers provide a flow chart for each pump.

But you may not receive this information until you actually purchase the pump.

Forget about being able to look up this information on the internet also, it just dosen't exist or is very hard to find.

So I have given you 3 examples of a relative common pond pump to base an educated guess of the size pump required.

Flow chart
Armed with the information from step 2 let's look at the 1800 GPH pump (in red).
At 125 GHP per inch this pump will produce a waterfall or stream of 14 inches wide at 2 feet in height.
The same pump and the same GPH per inch at 6 foot in height (remember step 2) will give you a waterfall or stream of 8.5 inches wide.
At 12 feet in height (remember step 2) it will produce a waterfall or stream of 7.5 inches wide.
So here is the best advice I can give you!
If you are planning a waterfall without a lot of tubing and is not very high I would go with your step 1 results.
If you are planning a stream that has a long pipe to supply the stream or a waterfall that has some height to it I would use step 2 and look carefully at the results.
If step 2 returns a result of greater than 6 or 8 I would consider doubling the size of the pump that is listed in step 1 of the waterfall pump calculator.

It is our hope that this waterfall pump calculator, stream calculator has helped you select the right size pump for your backyard project.

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