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Various
Water Garden Measurements |
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Ontario Water Garden Society Newsletters
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ONTARIO
WATER GARDEN SOCIETY |
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In deciding how densely you can stock your Koi pond, you should consider the following:
- How much time
are you willing to devote to care and maintenance? As mentioned above, you also need to factor in the growth of your fish. Lets suppose that you start with 6 Koi that are 6" long. Your initial fish weight is only 9 ounces. If they are well cared for, they could easily be 10" long in a year and 14" in just two years. At 14" each, you now have 114 ounces of fish, almost 13 times what you started with only two years earlier - and they're not done growing! You need to plan for this growth when designing your pond and filters and when deciding on whether your pond can handle "just one more Koi". So if we want our fish to remain healthy for many years, we should expect that we will have to provide the necessary level of care. In a commercial farm, if a fish gets sick, they just dispose of it. Unless you want to do the same, you can't stock your pond like it's a fish stick factory. For goldfish, the process will be similar but with the differences being they don't grow as fast or as large and generally require less care. Besides using these figures to determine filter and pond sizes, they may also be used when calculating doses of medications, adding salt or when determining how much to feed. Calculations for medicine or food would be based on actual volume and not the effective volume. This table also allows you to predict how much your fish will weigh in the future. Having some idea of future weight will help you make decisions such as "When do I need to upgrade my filter?" and "How big does my filter need to be?" Growth rates vary greatly. The chart below shows some (very rough) Koi lengths (in inches) for three situations: maximum growth, normal pond, and low growth. In the maximum growth scenario, the Koi are kept in water that is around 70°F to 75°F year round and are fed around 5% of their body weight daily (spread out over 8 to 12 feedings). The normal pond rate assumes that the Koi are fed twice a day in warm weather, less in the spring and fall, and none in winter. The low growth scenario assumes that the Koi are fed a little every few days in summer.
Impact of Total Head The terms "head" or "lift" are used to indicate the rise, measuring how high the water must be pumped for a particular application. The higher the pump must push the water, the less water will be pumped. Pumping water through tubing (to a waterfall, for example) adds resistance. To allow for friction loss inside the tubing, add one foot of head for every 10 feet of horizontal tubing run. Add the allowance for friction loss to the vertical distance (in feet) that you will be pumping the water. The vertical lift is measured from the surface of the pond. The resulting sum will be the TOTAL head that the pump will be required to pump. You should compare the amount of flow that you require to the flow rate that the pump provides at this specific head. Example Vertical distance between pond surface level and the top of the waterfall is 3 feet. You have 20 feet of tubing between the pump and the waterfall. Your total head is 5 feet. When purchasing a pump, the manufactures instructions or the dealer should help in determining the impact of 'total head' on performance. For the effect of each additional foot, there is no common ratio that could be applied to all pumps. A couple examples are a pump rated at 950GPH is 850 at 3' and 750 at 5', and one rated at 2,400GPH is 2,000 at 3' and 1800 at 5'. Note - on top of height and distance, you will need to add additional values if you are using rigid piping with elbows. For a 90-degree elbow add 32 times the pipe bore converted to feet. A 3" elbow has the same resistance as 8' of pipe (32 x 3"/12"). Add 8' for each 90-degree elbow to the total tubing when doing the total head calculation. For a 45-degree elbow use 15 instead of 32 in the calculation. If at all possible design your system without requiring these turns. Tubing Flow Rates The tubing size running from the pump is determined by the maximum flow rate of the pump you select. Pick the tubing diameter that is most appropriate for the volume of water coming from the pump. A hose adapter or a combination of adapters is required to attach the hose to most pumps. Following are the maximum flow rates in GPH for various tubing diameters:
Hint: If your pump does not deliver the amount of water it is rated for, perhaps you are using tubing that is the wrong size. Waterfall Flow Rates Appearance is an important consideration when operating a waterfall. The volume of water required too achieve different effects (robust waterfall vs. just a trickle) will depend upon the width of the waterfall lip (weir) or stream and the material that it is constructed from. The chart below will tell you how much water is required PER inch of waterfall width to achieve different thickness of water over the entire width of the waterfall weir. Using this chart and your 'total head' calculated above, it becomes quite easy to determine which pump to use.
Example You have a 3.5' tall (above the surface of the pond) waterfall and will have 15' of tubing run between the pump and the top of the waterfall. The total head is thus 5'. To achieve a 3/4" water thickness over the width of an 8" wide stone waterfall weir, you would require a pump that would produce 1600 GPH (200 GPH per inch x 8 inches total width - 5th line) at a total head of 5'. The earlier examples for 'total head' show a 2,400 GPH pump produces 1,800 GPH at 5' head, so for this waterfall example a pump rated around 2,250 GPH. should be about right. You can also use this chart to predict the effect that you will get from different volumes of water. Example If you use the same 3' tall and 8" wide waterfall as above with 15' tubing run, and you have a pump that only supplies 500 GPH at 4.5' total head, you would expect to get 62.5 GPH per inch (500 divided by 8) over the 8" width of the waterfall weir. As 62.5 is midway between 50 and 75 (line 2 and 3), the resulting water thickness would be between 5/16 and 3/8" thickness. How to Measure a Flow Rate This formula can be used to measure the flow rate of your pump. This is helpful to determine is a manufactures claim is correct or if an old pump is still working effectively. Take a container of known volume (i.e. a 5-gallon bucket) and time how long it takes to fill it (in seconds) at the flow that you have. Then divide 3600 by the number of seconds it takes to fill the container and multiply by the volume (gallons) of the container. The result will be the flow rate in gallons per hour. Example: It takes 10 seconds to fill a 5-gallon bucket. 3600 / 10 seconds x 5 gallons = 1,800 GPH You can also use this formula to decide how much flow you would like over a waterfall by placing a garden hose at the top of the waterfall and adjusting the volume of water until you find the flow that you like. Measure this flow and you will have an idea of the volume required to get the effect you desire. For more robust flow you would likely need multiple hoses. Using all these different calculations you should be able do determine any requirements for pumps and filters. There are a few websites which provide calculators which are also helpful. 1) www.aquaticeco.com. - there is a distance, weight and volume calculator. For volume you can enter one of liters, fluid ounces, quarts, gallons imperial gallons and the others will be calculated. 2) www.wernerponds.com. various calculations are done by entering length, width, max. depth, and average depth - one caution here is that this is fine for the liner size calculation but the if the pond is not rectangular, you will need to do a second calculation using average length and width.
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