Pond volume question

[pecan]

Hi!

I am day dreaming about another pond and was trying to figure out how many gallons it would be. I have always hated pond volume calculators since they always provide such different results

This pond would be 8 feet wide x 5 feet long x 4 feet deep. Perfect oval, long side being 8' and short side being 5' with a constant depth of 4'.

I have tried 4 pond calculators I found using google. 2 of which said it would be 1100 gallons and 2 said it would be 2100 gallons. Those numbers aren't even close... How can I have such different results ?

Does anyone know which is correct or if neither are correct?

 

[dieselplower]

If it was a square it would be 1200 gallons. Since it is a circle you do have to subtract the 4 unused corners of the square so I would say the 1100 number is close but possibly too high.

 

[pecan]

Thanks! In most of the oval calculators it asks for the radius. I calculated the radius as half the length plus half the width divided by 2 equaling 3.25. Is that a correct radius?

 

[pecan]

I just tried another calculator and which came to 125,000 gallons!!! LOL

I think 1000 gallons is about right though

 

[dieselplower]

Thanks! In most of the oval calculators it asks for the radius. I calculated the radius as half the length plus half the width divided by 2 equaling 3.25. Is that a correct radius?

Seems like it but I truly hate math and really don't recall

 

[slakker]

Using an estimation that the shape is an ellipse, then the Area=pi*(2.5*8)=62.8 sq ft, so volume=62.8*4=251.2 cubic ft or 1879.1 US Gallons.... I "R" an Engineer! LOL...

 

[slakker]

I R a bad engineer! Correction to the above... Area=pi*(2.5*4)=31.4 sq ft, so volume=31.4*4=125.6 cubic ft or 939.6 US Gallons...

Forgot to change the 8 feet across to 4 feet "radius" on the long side...

 

[pecan]

Bingo! So I think 1000 is about right then. As there would be a 70 gallon skippy, a small pool above the falls and a water fall. Thank you!

 

[Carolyn22]

Do you have a meter on your water in your cellar? This is how we know exactly what the gallons are in our pond.. We ran into the same problem that you were having with the different pond calculators.

 

[pecan]

Do you have a meter on your water in your cellar? This is how we know exactly what the gallons are in our pond.. We ran into the same problem that you were having with the different pond calculators.

No but I am thinking about getting one prior to this pond build. It would be a good thing to have as knowing exact gallons can come in handy. My big pond is anywhere from 4000 gallons to 6000 gallons. I always just say 5000 since I really don't know for sure. The new small pond would be a temp home for my fish while I dug the big pond deeper so a meter would come in handy when filling both.

 

[slakker]

Or you can get a fancy-schmancy thing like this...

http://www.leevalley.com/en/garden/page.aspx?p=70505&cat=2,2280,33160

 

[Carolyn22]

$12.50 is more than affordable too!

 

[pecan]

Yep $12.50, to know the exact gallons of a pond is a GREAT deal!

 

[crsublette]

Yeah, I highly recommend a good flow meter. They simply are very handy. When you are not using it, then you can install it on a bypass at the end of your filtration system to know exactly what type of flow you are obtaining from your pump.

I would be cautious about getting cheap meters due to their accuracy, but we do not need to be extremely accurate and the Lee Valley one slakker hyperlinked looks quite interesting. I would definitely test the meter after you got it. You can achieve this by simply filling a bucket with exactly 2 gallons of water, put in a fountain pump, connect the meter, and see how much water the meter actually counts.

If you want a higher quality meter that are quite durable and accurate, then checkout Grainger PVC Flow Meters; although, notice there is a minimum flow to them. For example, the 2" PVC grainger flow meter (which is $500~600) only accurately meters a flow range between 1200gph~12,000gph. I use these on the farm so I snag one on occasion when I want to meter my pond. Shh, don't tell anyone.

Of course, for what we're doing, you do not necessarily need extreme accuracy. Just need to know close enough.

I bet the Lee Valley one Slakker hyperlinks will work fine enough.

 

[rebelangel_3733]

It's really hard to figure out for sure what mine is...as the rain filled it 3/4 of the way for me. I guestamate it at 1900 gallons though...and I hate math period.