Problem with calculating...

[kelli]

Hi from a newbie! Only a little pond experience, but am starting something much larger than what I'm used to and really need to bend your ear,

I need to figure out what GPH pump we'll need, so I've been looking around online for a way to calculate volume, etc.

Problem is, we'll have a simple stream running into the pond and that kind of calculator doesn't seem to exist. Since I can't find anything to plug in all the numbers, I've entered the numbers for the pond, then the stream separately, and simply added the two together.

My (latest) problem is, I'm getting differing answers from various sites/people/places. Can anyone steer me to a reliable calculator or fill me in on why the numbers could come up so different?

The stream (gently propelled by a fall some 20-24 inches up) will be quite long (35 feet), but we're letting gravity do most of the work (great natural slope, and we're helping in the few tiny places nature lacked). It will lead into an 8 by 8 roundish pond. The pond itself is only going to be a couple feet deep, no fish, just plants.

Any hints on determining pond volume (or pump size for that matter) would be greatly appreciated. Thanks! (going back to read more! this forum is fantastic! hope I didn't miss the answer to my question elsewhere. sorry, if so!)

 

[kelli]

Awww come on. rofile: There has to be a pond-volume-math-whiz out there somewhere...

Since I posted this, I've gotten a whopping three more figures. I know it varies and isn't an exact science, but... Pretty soon I'm gathering the figures and taking the 'majority wins' approach.

:100:?

 

[koiguy1969]

legnth x width x average depth x 7.48 = pond volume

 

[kelli]

Hey, thanks!
I'd heard that, too. So let's take the pond portion.
8 x 8 x 2 - 128 x 7.48 = 957.44

Ok.

However this calculator:
http://www.your-garden-ponds-center.com/pond-volume-calculator.html
gives me 752.


The stream- I figured 35 x 3 x .5 x 7.48, which gives me 392.70.


A woman on the phone at a local(ish) pond place calculated the entire thing to be 1200. I get 1350. Someone else got 2200. Wha?

There area even more figures from other sites/people.

I called Skippy's. No answer.

rofile:

I'm going with majority and the 1350 figure. Done.

The (other) issue is, if I am correct with the 1350 figure, having never put in a waterfall or run pipe this far, would I need something even stronger than a 1350 GPHs-ish size to do all that work?

Thanks for any input.

 

[David]

I created my own calculators.
If I take the number of 8*8*2 and plug it into the round pond calculator I do get 752.
To calculate a round pond you need to include pi into the math.
This is part of the script that calculates a round pond.

// then compute the gallons based upon the formula
var gallons2 = ((1 * 3.14) * (radiusa / 2) * (radiusb / 2) * averagedepth2 * 7.48051945);
g.gallons2.value = Math.round(gallons2);

I had a hard time with this calculator because

1) I could not get it to work without multiplying pi * 1
But 1* any number will give you the same number.

2)To calculate the volume of a round pond you need to use the radius of the pond in the math.
But I did not think that people would know the radius, but they would know the length across the pond so I divided that number by 2

For an oval pond one of the radius numbers would be larger.

This is part of the script that calculates a square pond.

// then compute the gallons based upon the formula
var gallons = (length * width * averagedepth * 7.48051945);
f.gallons.value = Math.round(gallons );

I did have a few calculators that needed to be fixed but that was because I used math round in the variables.
This would not let people enter a decimal point but would change there number to a whole number.

If anyone wants a calculator for any math problem just ask and I can write the script and include it on my site.

Or I just may be willing to share with other webmasters.

If you find that I have a calculator that is wrong or needs something just ask me.

 

[David]

So I entered the stream numbers into the sq. pond volume calculator and came up with 393 gallons.
You came up with 392.70 gallons and I came up with 393 gallons on my site.
But I use math round, so I would say that 393 is a good number for your stream.

Then I entered your numbers of 8*8*2 into my round pond volume calculator and came up with 752 gallons.

So 752 + 393 = 1145 gallons

The lady at your local pond place came up with a total of 1200 gallons.

I think that 1145 is a true number and the lady at the pond store used math round in her head and rounded it to 1200 gallons to make it easy on you.

That is if you are planning a round pond and not a square pond.

I did not see anywhere in your post about the shape you are planning, or did I miss something?
_________________________________________________________________
I also have a calculator that calculates the head pressure that is placed on your pump.

It takes into account:

Gravity (how high you are lifting the water)

Resistance (how many fittings, bulkheads, 90 degree elbows, reducers)

Friction (the length of your pipes)

And yes it is one that I created.

But I find that it is also very true in calculating the head pressure that is placed on your pump.

________________________________________________________________
As for your stream use the waterfall calculator.

You are looking for a flow of water for your stream just as you would for a waterfall.

O and buy the way it also includes the head pressure calculator in the calculation.

As far as I know I am the only one on the internet that has this type of calculator (waterfall calculator and head pressure calculator all in one).

Let’s say you went on line for a waterfall calculator and for the waterfall that you want it sad that you need an 800 gallon per hour pump.

But how high are you pumping the water?

How long is your pipes?

Fittings, filters, reducers?

So by incorporating the head pressure into the waterfall calculator I believe that my waterfall calculator is very true.

 

[KevinN]

legnth x width x average depth x 7.48 = pond volume

Just a curious question. I get the length x width x depth, but what is with this 7.48???

 

[David]

One cubic foot of water contains 7.48052 gallons.

 

[DrCase]

I got to remember that David
If i need a ? answerd it would just be easyer to ask you for the answer.:icon_mrgreen:
I just look at the water meter and see how many gal it takes to fill it up.

 

[kelli]

Wow!

When I asked for a math whiz, I didn't realize I'd get an ACTUAL math whiz! David- thanks!

Yes, you're correct- the pond is round. Most of the other info is in the first post:
The stream (gently propelled by a fall some 20-24 inches up) will be quite long (35 feet), but we're letting gravity do most of the work (great natural slope, and we're helping in the few tiny places nature lacked). It will lead into an 8 by 8 roundish pond. The pond itself is only going to be a couple feet deep, no fish, just plants.

We do want it to be a smooth, soft flow. No rapids or anything. Animals will be drinking from the stream, so... it's really a glorified water fountain. (but prettier)




Thanks again for all of your expertise and assurance. 1200 it is.
Now I'm off to check out that pressure calculator and I'll be on the road to getting the correct pump size. =)

(..and I did get in touch with someone at Skippy's. She said to go with anything from an 1800 to a 2400. Too broad of a range for me.)

 

[kelli]

Found it!

http://www.your-garden-ponds-center.com/head-pressure-calculator.html

(great site, by the way!)

But, yep. That's what I was afraid of.
Still not sure what GPH to get.

I plan on visiting Skippy's over the next few days and will see what they say. The woman on the phone was SUPER nice.

David, if you have an idea what I should get based on the specs I've given thus far and want to give me your recommendation, please do! rofile: Thanks!

We're running 2 inch pipe the 35 feet over to the filter, but if anyone thinks it should be bigger for any reason, please feel free to shout!

 

[BBK]

The only way to find out for sure is to take a gallon milk jug and spend a weekend filling it up.

 

[kelli]

Great! When can I expect you?

 

[BBK]

I will gladly do it, I charge $15 an hour and you provide the beer.

 

[kelli]

Smart ass. :icon_mrgreen:
(whoops! can I say ass on this forum? no? avert your eyes!)

Hey now... If I can't figure out how many gallons per hour the PUMP will run through, how can I be sure about YOU? What if you're a slow worker? I need to make sure I'm getting my money's worth!

$15 & beer, too? Sigh.