Choosing the right waterfall pump in practice
I received a very nice and very practical request for help from a lady called Lynn which I think may help a lot of my readers. This is the first letter ....
I realize that you are probably a very busy man in high demand, so if you don't have the time to answer my email, I will understand. Being a woman, and on my own, pumps and filters and mechanical things are a little more of a challenge for me than they might be for your more "technically oriented" male readers. So any advice you can give me will be taken to heart.
I have read and re-read the information located on your website. It is so refreshing to find someone who is actually trying to help people and save them money at the same time. I find all of the information fascinating, but there is so much information that I am becoming overwhelmed and confused as to what would actually do the best job without spending up into my food money.
I had no idea that ponds were so involved. I have had a 14" deep, (I hit hard rock and had to stop digging or it would have been deeper) by an average of 8 feet wide, and an average of 18 feet long pond for about 5 years. I have been replacing the sump pump that runs the waterfall every single spring and it is not satisfactory. (notice this is my emphasis). I have no idea how much the water volume is in my pond.
How do I figure out what size pump I need to do the best job? Here are my details:
The head of my waterfall (which is a sprinkler like device that sprays) is 3 feet from the surface of my pond. I used a protractor, some paper, and some guess work and have figured out that the grade or slope of the pipe run up the small mound is around a 35% to 40% grade. The "run" of pipe up to the head of the waterfall is about 28 to 30 feet.
With all of this information I have found on your site and using the charts and values on them, I still cannot figure out what size pump would be the most efficient, durable, and able to be eventually connected to a filter.Could you help me out a little?
Next month, when I have paid off the pump, I would like to invest in one of the nice dependable UV and biological filter system. Knowing something about my pond size, would there be a filter that would work well with the type of pump you might recommend?
I realize that you probably receive many letters like mine, but my hope is that you might at least have some idea of what will work the best. Is your pond book available at bookstores like Barnes and Noble or Borders Books? I would really like to have a good book to use for reference, and yours looks like a really informative one. Thank you for any help you might give me.
Smiles,
Lynn
My comments are in RED ...
Using a sump pump is bad news as you now know of course. The reason is that they are not designed for continuous running and when they are used continuously their useful life is dramatically shortened. ... they also use a lot of electricity. Any body using a sump pump should look at replacing it with a low efficiency pump like those made by Danner in USA.
The length of pipe is not that important but diameter is very important especially if pipe is long (like your pipe is)
Almost any pump can be used to supply a filter ... this is not a critical application in terms of volume but your waterfall is very much volume dependent. So the Danner pump chosen will almost certainly be good enough for your pond filter too.
To be able to correctly specify your waterfall pump. I need following information ...
1. If you imagine water is falling in a single sheet how wide would that sheet be (this is what I mean when i refer to a waterfall LIP)
2. Height above pond surface (I think you say 3ft) but I need more clarification on the spray device you mention
By the way Your pond volume based upon the dimensions you gave (8 feet x 18 feet by 14 inches deep) is 1,250 US gallons or 1,050 UK gallons (both approximate values but good enough) or in litres about 4,500
Second letter ....
Dear Tony,
Thank you for replying to my questions about pond pumps and filters.
To answer your questions. My father made a chunk of aluminum into a sprinkler type of device that fits on the end of the 1" plastic pipe at the end of my run of pipe. It is a triangular shaped piece of metal about 6" wide at the outlet end and tapers back to about 2" wide at the end where it fits onto the pipe ( slot is 7 to 8 inches wide). The device is about 1" thick, and flat. He shaped it inside so that the water would flow through the slot at the wide end and mimic a waterfall style of spray.
The reason he made that for me was because the water was leaking out of the pond when it ran over the rocks naturally. It was flowing over the large rock at the bottom, going down the face of the rock, and seeping behind the pond liner no matter how tightly I sealed it to the rocks. I realize now that I should have set the rocks on top of the liner when I built the pond, but it's definitely too late now. With the waterfall "head" on the end of the pipe, it pushes the water out and over the large rock and there is no back seepage.
The pipe running up to the head is 1 inch in diameter. The pipe run is about 30 feet. The highest point where the pipe goes is actually about 3 1/2 feet to 4 feet from the surface of the pond, but the device is lower than the highest point and is about 3 feet from the surface. The pond is an average of 18 feet long, by 8 feet wide, by about 14 inches deep. Using a protractor and holding it up to the slope, it measures about 35 to 40 degrees of a slope.
Thank you so much. Any help will be greatly appreciated. I looked at the Danner pumps and was very impressed. Those are the ones I wanted to purchase.
Thank you for replying to my email, and thank you again for your help.Smiles, Lynn : )
Lynn
Here's my suggestion as to how to decide which pump you need.... I cannot calculate your volume so you need to determine it practically. The reason I say I cannot calculate your volume is because you have an unusual outlet for your waterfall. Anyway this way applies to any waterfall because you can always simulate a waterfall by using a hose pipe as explained in previous gazettes
DETERMINE VOLUME THIS WAY ....
1. With the waterfall running just as you like it
2. Use bucket to collect all water coming out of spray device
3. Measure time to collect the water in the bucket
You can then calculate the flow as follows ....
1. If possible collect exact volume eg 5 gallons, 10 gallons etc
2. If you cannot do this then after collecting the water pour the collected water into coke bottles or something similar .... these bottle volumes are then known so it is a matter of counting how many bottles you fill from the bucket and multiplying volume of water in a single bottle by number of bottles you filled
You now know how much water came out of waterfall in a specific time (because you measured time to fill bucket) and you can pro rata work out flow per hour
ALTERNATIVELY (and much easier} If you have a scale you can weigh bucket empty and then when full ..... 1 gallon of water weighs 10 lbs (in UK gallons) and 1 US gallon weighs 8.34 lbs
DETERMINE HEAD THIS WAY
As you describe your system the height water must be pumped to is 4 feet (if in doubt go a bit higher ... you say between 3 and half and 4 feet so I have taken 4 feet not 3 and half to be on safe side)
Now in your case you have long pipe and it is 1 inch diameter.... using my calculators you can work things out very accurately but since I do not know volume I cannot do this. However my experience suggests from your general description that you should add 4 feet more pumping height to compensate for the long pipe and the pressure losses in this pipe as well as the unusual outlet slot ... make sure your pipe is not kinked and reduce number and severity of any bends in the pipe
DETERMINE PUMP SPECIFICATION THIS WAY
Once you determine volume you will look for pump that will pump that amount at (4 + 4) = 8 feet high and you have solved your problem
If in doubt always go a pump size higher Finally if you provide me with volume I will advise you exact Danner pump to buy.
Go here to select the correct pump for your own pond or waterfall
Your question was a good one because it relates to real practical situation and not a simple thoeretical one.
I will use this in my newsletter
2. Some Hints on Building Your Own Waterfall using Liners and Rocks
It is not easy to build your own waterfall using liner when slopes are involved. It is not my intention in the gazette to go into great details. Rather I want to point out where the difficulties lie and the broad solution available to you ....
You need to build a frame work for your planned waterfall ... you cannot just place a piece of liner on a slope and then place rocks around the edge. rather create a series of terraces so that each terrace cascades gently into the next lower one.
Each terrace should be a like a small self contained pond with edges to prevent water being lost from the sides and of course an outlet. So you dig a series of suitably sized holes making the base of each hole flat .... you will do this by digging into the slope of soil
Each "small pond" must be able to support itself ... ie the walls will not collapse when it rains for example so by far the best way is to use a firm base and build up the sides using bricks or blocks as if you were building a shallow concrete pond.
The outlet lip for each "small pond" must be 4 inches lower than the pond brickwork.
Once completed place the liner in position and make sure it overlaps the brick edges down the length of the waterfall. You can then place a final layer of bricks or rocks or whatever to hide the liner edge that passes over the brickwork.
Pond plants for this season
Pond plants ... every garden pond should have some (even those small barrel ponds I discussed last time). Here are some suggestions for this season and where you can get them on line ... click the image banner below and then choose Water Plants once you get to home page
They have nice basic variety of water lilies for sale ... every pond should have a water lily or two. There is also a wide range of marginals too. Well worth a look Other plants available ... see the pictures at my web site by clicking the link not placed here to reduce download time
