Size of my pond

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I am trying to determine the size of my pond in volume.

It is a highly irregular boundary, and what makes it trickier is the depth also vary greatly.

IMG_20221101_183235.jpg


I recently did a complete cleanout, and yesterday after hurricane Nicole left the pond was full again from the rain, so I drained it with a small utility pump. It is an Everbilt 1/4HP utility pump and it's specifications says "Flow rate: submersible utility 1600 GPH".

However it took 4 full hours to fully empty the pond. If it is truly doing 1600GPH then the pond has 5400G? I had previously did a rough area (very rough) and multiplied by an average depth of 2 feet and came to about 1000G.

What is a good way to accurately determine it's volume?
 
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You can estimate by taking good measurements and turning the whole space into a series of geometric shapes. Measure volume of all cubes and add them together.

Or you can get a $15 flow meter for your garden hose and meter it the next time you fill up. Then you'll know for sure.

As for your pump, most are lying through their teeth with their advertised flow rate. And when they aren't the advertised rate will only be applicable when it's pumping in perfect conditions with no discharge hose attached. If you were draining your pond through a long 1/2" garden hose or something, that will significantly reduce your flow rate.

If you want to know the flow rate you're actually getting, time a 5 gallon bucket fill. Divide 5 by the seconds to fill then multiply by 60 and multiply by 60 again. That's your true GPH. Keep in mind that rate will change (lower) as you drain the pond down since lower water level = more head pressure for the pump to overcome.

Best to just get the hose meter...
 
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A rough estimate is generally good enough. There are lots of pond volume calculators on the internet - here's one example:


Just put in width, length and average depth and you'll have a good estimate.
 
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It IS hard to judge though...Most of us have shelves in our ponds and different depths...I think the flow meter that combatwombat suggested would be the most accurate if you want an exact amount of gallons:)
 
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I will get a flow meter to get a better idea.

I did do some measurements and location today of the pond's perimeter at the usual water level. I then input that to a CAD software.

pondareas.jpg

The blue section is 116SF and the beige section is 56SF. I would estimate the blue section average depth is 28" and the beige section at 12" depth. That would put it at 326CF total. Converting to gallons that is 2438 gallons.

That is probably overestimating because around the perimeter the edges slope up (instead of a vertical face) and I haven't account for the bridge pier and other irregular pieces.
 
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Well, I couldn't find a flow meter locally in plumbing supply stores or big boxes, all they have are irrigation flow meter/timer combos. It is more to run the device until a certain preset volume has passed or a certain time has elapsed. So I end up ordering a hose end flow meter from Amazon.

312FXn+W5lL._AC_.jpg


My pond was full from a recent rain storm, so I attached a garden hose to the flow meter on one end, then a utility pump on the other end, and turned the pump on. It was fine for about 0.3 gallons before the meter stopped. I took the meter off and can see some debris inside, some muddy seeds. Once I rinsed it out it worked again.

This time I dropped an 8" concrete block into the bottom and sat the pump on it so it is elevated to reduce the amount of debris it sucks in. Well about 1.2 gallons it jammed again. The suction is pretty good then.

There are all kinds of debris at the bottom, twigs, seeds, fruit drops, leaves, mud...I cleaned it multiple times over the last month but leaves are dropping every day.

So I cleaned the flow meter out again. This time I got a large plastic nursery pot, and I got one of those sheer window curtain liner that has a very fine mesh, and wrapped two layers of that on the outside of the pot, the idea is to use that as a filter as water runs into the pot from the three holes on the bottom. I guess good idea in theory but about 3 minutes in the suction is such that the mesh got ripped through the holes where water was entering due to the suction. So debris got in again. I didn't tell my wife I borrowed the curtain and I quickly disposed of it before she found out.

So now I am back to the same place about trying to determine the volume of this irregular shaped irregular depth pond. I know I can measure it by filling it with clean water, but since it rains here so often, I hate to waste 2000 gallons of city water just to determine the pond volume when usually it's filled and topped off by rain.

Anyone know of a flow meter that is more tolerant of debris passing through it?
 
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Start hauling 5 gallon buckets. Set up 2 buckets. Pump into one bucket until full. Switch to 2nd bucket while you kick over set back up the first. Repeat until the pond is empty or you get bored and give up. Might need a friend to keep tally!

Yes, those little flow meters depend on a tiny little turbine to spin and cannot handle even the slightest debris. There are other ways (ultrasonic) to measure flow through a pipe, but that would be kind of ridiculous for finding the volume of a garden pond.

One question to ask yourself: Does it matter that much?

I didn't tell my wife I borrowed the curtain and I quickly disposed of it before she found out.

It's the only way to do it. I almost got caught using the wife's lipstick when I couldn't find my grease pencil the other day. Better to just throw it away and blame it on the dog.
 
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Does it matter that much?
Well it probably isn't a great deal. The only thing is now that I have been trying to do it, tried this, tried that, it has kind of gotten personal, and I know once I am done and fill it back up I won't have the luxury of a total empty pond to do any other measurements for a long time.

and my wife hasn't discovered the missing curtain yet haha.
 

addy1

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My pond gallons are all guess work. Never worried about it that much. Did try a hose flow meter when filling, it failed, I just ran the hose for a few weeks off and on until it was full. We were in a drought and we are on a well.
 

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