Monday, March 12, 2012

Building Our Waterfall Part 3: Sizing The Waterfall


With the catch basin correctly sized, 
the next step is more interesting: 
determining the flow of water 
over the waterfall.

The components of a disappearing waterfall include the waterfall catch basin as the source of the water, a submerged pump in the catch basin that circulates water through tubing up to the head of the waterfall where it empties into a weir (this is just a box which diffuses the water to create a natural appearing waterfall) before spilling over the lip of the weir and cascading down to the rocks below. Gravity then encourages the water down the stream-bed if you have one, where it collects in the catch basin, ready for the return trip up the tubing.

In order to size the pump, 
you need to decide how much water you want to flow over a waterfall. 

Half-inch deep waterfalls are common for residential water features, which really is plenty to give you a sound that you will enjoy. The Waterfall Flow Calculator will reveal that wider waterfalls and deeper flows come with a cost—the need for a bigger pump. Note that the resulting recommendation of the calculator (in gallons per hour, or gph) is how much flow you need at the top of the waterfall. 

Calculating the Pump Size

If the recommended flow at the top of the waterfall is 1,200gph, you will need a pump rated at more than 1,200gph, since you will need to factor in the amount of force needed to push the water to the top of the waterfall. This force (also known as head pressure) is influenced by the height of the waterfall, the length of the tubing you are using, and the fittings used to connect the tubing. Pumps are rated at being able to deliver a quantity of gallons per hour depending on the head height, which really means the calculated head pressure—not simply the height of the waterfall. This Head Pressure Calculator will tell you the height of your waterfall as perceived by the pump.

For example, if your waterfall is 3 feet high, and you have one 90 degree fitting, 15 feet of pipe, and two other fittings, this would be equivalent of lifting the water 8.5 feet high. When shopping for pumps, you will need to find one that delivers 1,200gph at 9 feet head height, not 3 feet.


Once we knew the correct head pressure for our waterfall,
we could then select the right pump.
After researching our choices, 
we purchased a 1200gph Atlantic TidalWave2 hybrid pump 
from our local sprinkler supply store that proved very capable.


♦  ♦  ♦


The waterfall and stream begin at the waterfall weir. 
Here’s a good picture of a weir
As you can see, they can be expensive. 
Next post I’ll show you how to build one for much less.


10 comments:

  1. Wonderful, Carolyn! You have given me inspiration!

    ReplyDelete
  2. Donna@Gardens Eye ViewJanuary 9, 2013 at 7:56 PM

    Wow I knew there was a good reason to hire someone to build my pond and waterfall...I am learning so much!

    ReplyDelete
  3. Actually Donna, we're trying to convince you that if a Grandma and Grandpa like us can build this amazing waterfall, certainly most anyone can do it themselves as well. Having a plan, and working the plan is key. What we didn't know, we googled, and we're sharing our best resources through this series.  

    ReplyDelete
  4. Actually Donna, we're trying to convince you that if a Grandma and Grandpa like us can build this amazing waterfall, certainly most anyone can do it themselves as well. Having a plan, and working the plan is key. What we didn't know, we googled, and we're sharing our best resources through this series.  Besides, if you hire a contractor... you miss out on all the fun!

    ReplyDelete
  5. Give it a go, and let us know how much fun you had!

    ReplyDelete
  6. Oh, you are a  a temptress if ever there was one!!!

    (Your husband may rest assured, though, that I am mainly tempted to a) build a water feature and b) read your next entry.)

    ReplyDelete
  7. The Sage ButterflyJanuary 9, 2013 at 7:56 PM

    this is so helpful, and I appreciate your attention to detail in explaining each step. When my husband and I build one, we will know how.

    ReplyDelete
  8. I really admire all your hard work making a waterfall, and showing us how to, also.  I've dreamed of putting in a waterfall down by the big pond, but that will be years and years away.  I still look at your instructions on putting in a flagstone patio, and dream.  You amaze me!

    ReplyDelete
  9.  I don't think a waterfall would really be right for our garden, so if/when I do a water feature it's more likely to be a miniature pond, probably with a small pump to keep the water aerated.  (We already have the soft sound of running water from the stream behind the house, so it would mainly be to create a habitat for frogs and toads in order to control our slug infestation. Surely that would be a pretty way to fight pests, right?)

    ReplyDelete
  10. Merci pour les explications. Good day.

    ReplyDelete

Welcome to my gardens!
Your comments are the sweet nectar that keeps me posting.
So glad you stopped by!