|Better Farming Series 29 - Freshwater Fish Farming: the Pond (FAO, 1981, 43 p.)|
|Building a bigger pond|
86. You will need an outlet to let water out of your pond when you want to empty it.
87. You should place the outlet at the bottom of the bank at the lower end of your pond at the deepest part.
88. The outlet can be made from a piece of heavy bamboo or a pipe of plastic or metal. The outlet pipe should be about 10 centimetres in diameter. The bank of your pond is much wider at the lower end than at the upper end, so the outlet pipe will have to be longer than the inlet pipe.
89. The outlet pipe should be long enough to reach through the bottom of the bank from one side to the other. You will need a pipe about 6.5 metres long to reach through the bank at the lower end of your pond.
90. It you cannot get a pipe that is long enough to go through the bank, you can join shorter pieces of pipe together using straight pieces of pipe like the ones in the drawing.
Join using straight pieces
91. If you are using bamboo, you can join short pieces of bamboo together with pieces of smaller bamboo in the centre, but the smaller pieces should be at least 8 to 9 centimetres in diameter. Wrap the bamboo joints with rope and close them with tar to keep water from seeping out.
Rope and tar
92. Now dig a gap in the bank where you want the outlet to be. It should reach from the deepest part on the inside of the pond through the bank to the outside of the pond.
93. If the outlet pipe is below ground level on the outside of the pond, you will have to dig a ditch to take the water away from the outlet.
Take the water away from the outlet
94. Put the outlet pipe in the gap in the bank and rebuild the bank over it.
95. If you use an outlet of about 10 centimetres in diameter, it will take about half a day to empty your pond.
96. It is easier to place the outlet where you want it to be before you dig out the centre of the pond and build the banks. When you build another pond, you will understand this and you will be able to do it when you are building the banks. But now, when you are building your first pond, you should place the outlet in the way you have just learned in this booklet because it is easier to understand.