|Better Farming Series 29 - Freshwater Fish Farming: the Pond (FAO, 1981, 43 p.)|
|Building a bigger pond|
103. If there is too much water in your pond, some of the water may flow over the banks. This may wash the banks away and some of your fish may get out.
104. You can use an overflow to keep the water in your pond from rising over the banks.
105. The better outlet you learned about in Items 97- 101 will act as an overflow.
106. If you use a straight pipe outlet or a siphon to let water out of your pond, you will need another kind of overflow.
107. This kind of overflow can be made from a piece of bamboo or a pipe of plastic or metal. The overflow pipe should be about 6 centimetres in diameter.
108. The overflow pipe should be long enough to reach through the top of the bank from the inside of the pond to a place far enough on the outside to keep overflow water from washing away the bank. You will need a pipe about 4.5 metres long to do this.
109. If you cannot get a pipe that is long enough, join short pieces of pipe or bamboo together. (see items 90 and 91).
110. It is best to place your overflow in the bank at the lower end of your pond right above the outlet so that the water that overflows can run off in the outlet ditch.
111. If you are going to put the overflow over the outlet, you can put it in the same gap that you dug for the outlet in Item 92. The water- line should be about 50 centimetres below the top of the bank, so put your overflow there as you rebuild the bank.
112. If you are going to put the overflow in another place, you will have to dig another gap in the bank about 50 centimetres deep.
113. When the pond is full, the overflow will keep the water about 60 centimetres deep at the shallow upper end and about 90 centimetres deep at the deepest Dart.
Keep the water deep