I have a pond that is irregular shaped and the depth also vary in multiple stages which makes it impossible to estimate it's volume by calculation.

So I decided to buy a $20 flow meter online. The idea is when I drain the pond when full I can attach one of these to the end of the utility pump hose end and it will tell me when it's fully drained how much water has passed.



Sounds good in theory but doesn't work in practice because of debris at the bottom of the fish pond. I have mud, leaves, seeds, fruit drops, twigs, all kinds of stuff that may get sucked into the hose and when they passed through the flow meter it jams the meter and the count stops. I can see there is a little wheel inside that spins and that's how it tracks the amount of water passing through.

So I got smarter, or so I thought. I used a dental pick and cleaned the flow meter so it's all clear and working again. Then I used a large plastic pot, and put a nylon mesh around the pot, then sat the utility pump inside the pot, thinking the nylon mesh will act as a prefilter and only allow water to pass into the pot for the pump. That worked for about 2 minutes before the nylon mesh got ripped by the suction of the pump through the pot and debris got sucked in again.

Is there a hose connection meter that is more tolerant of debris running through it?

My other option is to not use the flow meter to drain, but when it fills. But I hate to waste 2000 gallons of water just to calculate the volume because normally the pond is filled by rain water. If the pond is empty all I need is a down pour or two over a weekend and it will be full. I only need to use city water to top it off a few times during the dry months and there is really no dry month in Florida.

Just a thought. How about using aluminium window screening instead of the nylon mesh?

not impossible

difficult to be sure

calculus will do the trick

but not by myself - i am ignorant



glad to see you are still 'machinating'

HAPPY NEW YEAR

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Calculus still needs a formula.

As per Penn State U:

Irregular Shaped
Many ponds have an irregular shape where the surface area cannot be adequately estimated using the formulas for common geometric shapes. Three methods can be used in this case depending on the degree of accuracy you desire. Keep in mind that the accuracy of your pond surface area estimate may be very important, especially for the safe use of aquatic herbicides. The three methods are described in order from least to most accurate. You should strive to use the most accurate method that you can reasonably accomplish.

Average Length and Width Method: Take numerous measurements to determine the average length and average width. Make certain you get both the longest and shortest distances in calculating the average length, and the widest and narrowest distances for determining the average width. The more measurements that you make, the more accurate your result will be. The area is then calculated by multiplying the average width times the average length. If you do your measurements in feet, your result will be in square feet. You can convert square feet into acres by dividing it by 43,560 ft2 per acre. Depending on the number of width and length measurements made, the final area will probably be within about ±20 percent of the actual pond surface area.
Multiple Trapezoids Method: A more accurate method to determine the area of an odd-shaped pond is to divide the pond into multiple trapezoid shapes. A new trapezoid is defined anywhere the shoreline makes a rapid change in direction. Note that instead of horizontal transects, this method requires measurement of the distance between each vertical transect. This would be most easily done during winter when the pond is frozen and the transects could be easily laid out and measured. This method requires more measurement and effort, but the final area estimate will probably be within ±5 to 10 percent of the actual pond area.
Handheld Global Positioning Systems (GPS): Handheld GPS systems have become quite common over the past five years as they have become more affordable. They are now routinely used for outdoor recreation (hunting, hiking, camping, etc.) and navigation. GPS units allow you to determine your exact location on earth using multiple satellites in space. Various locations, or "waypoints," can be stored in the GPS unit for use with mapping software that either accompanies the unit or can be purchased separately. The software can connect the waypoints and calculate the area inside the resulting shape.
Geographical Information Websites: There are also geographical information programs on the internet, like Google Earth or Bing Maps, which use satellite imagery to display a map of your pond or lake. These website tools can make it very easy to determine the surface area of your water resource.
A pond surface area could be estimated by walking the perimeter of the pond and stopping at various waypoint locations along the pond shoreline. If waypoints are stored at each location where the pond shape changes, the resulting area will be extremely accurate, probably within 1 percent of the actual pond area. Even if you do not own a GPS system, friends or family members that enjoy outdoor recreation may own a unit that could be used to estimate your pond surface area.

Pond Depth and Volume Measurement
The volume of water in ponds is often expressed in units called "acre-feet." An acre-foot represents one surface acre that is one foot deep. To calculate the acre-feet of water in a pond, you'll need the surface area in acres as calculated above and an average depth of water in the pond. For a typical bowl-shaped pond the average depth can be estimated as 0.4 times the maximum depth. So, a pond with a maximum depth of 12 feet would have an average depth of about 4.8 feet.

A more accurate method for calculating average depth is to make many measurements and calculate an average. This is most often done by measuring the pond depth along two transects--one along the width and one along the length. Make sure to pick transects that represent the shallow and deep portions of the pond. Depths can be measured easily from a canoe or boat using a weight and a string marked in feet. The more depth measures that you make, the more accurate your final average will be. In the example shown on the next page, pond depths were taken at six locations across the pond length and five locations across the pond width. The average pond depth can be calculated as the average of all of these measurements.

The volume of water in the pond (in acre-feet) is calculated by simply multiplying the pond area (in acres) by the average pond depth in feet. Keep in mind that one acre-foot of water is equal to 325,851 gallons.

An even better way to calculate an average pond depth is to divide the pond into numerous (at least four) sub-areas (much like we did in the trapezoid method). Take at least one depth within each of the sub-areas and use these to calculate the overall average pond depth. This method is especially good if the pond bottom is irregular rather than bowl shaped.

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Agree with the aluminum screen. You had the right idea with the pre-filter but not constructed properly. I have to ask....why do you want to know how many gallons the pond holds?

I don't need to know the exact amount down to the decimal. But the volume of a pond is an integral part to determine many things.

Some of it is chemistry. For example if you are filling up a pond with city water you need the volume to calculate how much declorinator to add to make it safe for fish. You also need to know if you ever need to add medication for fish to the correct concentration.

You also need to know the volume in order to size the pond pump, as well as how long to keep the pump running. For example if you have a 1000 gallon pond, and your pump cycles through 1000 gallons every 2 hours, so if you want to cycle all the water through it twice a day, you can set your timer to run 4 hours a day to achieve that result.

It also goes into some rough calculations of how many fish it will fit, how many water plants to keep in the pond, and if you get into biological filters and stuff it is important in calculations there too.



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Good info, thanks Sum!

Sum,

All this comes from hanging out with Koi pond guys for 10+ years.

Regarding volume, you wrote: "But I hate to waste 2000 gallons of water just to calculate the volume". Perhaps I misunderstood, but it sounds like you know the pond is approximately 2000 gallons? The koi pond guys all estimate the volume, double it, then buy the next larger pump. An oversized pump will last longer, pump faster, and withstand debris better. Undersized pumps cause problems, oversized pumps solve them.

Regarding the dechlorinator: Double or triple dosing does no harm at all. Most municipal water systems have transitioned from chlorine to chloramines, so make sure to use a commercial dechlorinator like Prime (my favorite) or Amquel. Sodium Thiosulfate only deals with chlorine, not the ammonia component of chloramines.



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