Pump size

Discussion in 'Water Features' started by Lombardi, Jun 11, 2004.

  1. Lombardi

    Lombardi LawnSite Senior Member
    Messages: 538

    What size pump would you recommend for this potential waterfall? They will be getting the water from the lake directly below. It is approximately 35' down to water and on a very steep slope.
    Any suggestions on the construction of the waterfall would be helpful also. Thanks in advance.

    cain before 1.jpg
  2. The Lawn Boy Pro

    The Lawn Boy Pro LawnSite Bronze Member
    Messages: 1,217

    something that pumps at LEAST 5000 GPH.
  3. Victor

    Victor LawnSite Bronze Member
    Messages: 1,430

    That's a really good site to build a waterfall on. I'm sure it will look great when you're done with it. I just read your question and figured I'd try to help.

    Let's talk waterfalls....... The sheet of water that flows over a waterfall is called a "weir." There are calculations that will let you determine how many gallons per minute of flow will be required to get a weir of a certain width and thickness. For example, if you had a waterfall weir that was let's say 6" to 11" wide, to have enough flow to make that weir 1" thick, you'd need to have 3300 gallons per minute of flow through that waterfall opening. If you had an opening of let's say 12" to 15" and you wanted your weir to be 1" thick, you'd need to have 4500 GPM of flow to acheive it. There are charts in pond building books (one of mine has one, but that won't do you any good) that lay out how much flow you'll need to achieve a weir of certain thickness given a particular width. Here's the web address of a chart you can look at for weir size calculations. >>

    Here's a rough guide that will get you started. This will at least give you an idea of what you'll need as far as pump capacity.
    Waterfall Weir Rates

    Width of Weir Thickness of Water

    (GPH/GPM per ft) Smooth Weir Stone/rough Weir

    360/6 1/4" 3/16"

    600/10 3/8" 5/16"

    900/15 1/2" 3/8"

    1,680/28 3/4" 9/16"

    2,400/40 1" 3/4"

    4,500/75 1.5" 1.25"

    6,720/112 2" 1.75"

    Once you figure out how much flow you're going to need to get your weir looking the way you want it to, simply select a high head pump (one that's made to elevate water great distances) that's rated to flow the amount of water that you want to move.

  4. WeatherMan

    WeatherMan LawnSite Senior Member
    Messages: 692

    Very good answear victor, you just keep amazing me with your knowledge
  5. Ground Master

    Ground Master LawnSite Senior Member
    Messages: 505

    Victor- you mean 3300 gph and not gpm, right?
  6. Victor

    Victor LawnSite Bronze Member
    Messages: 1,430

    That's right....GPH........sorry about that.

  7. Victor

    Victor LawnSite Bronze Member
    Messages: 1,430

    Thanks Weatherman. I still have a lot to learn though.


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