Cover Image
close this bookBetter Farming Series 29 - Freshwater Fish Farming: the Pond (FAO, 1981, 43 p.)
close this folderBuilding a bigger pond
View the documentHow to make your old pond bigger
View the documentHow to build a new, bigger pond
View the documentThe inlet
View the documentThe outlet
View the documentA better outlet
View the documentThe overflow
View the documentA siphon
View the documentScreens

A siphon

114. You can also use a siphon to empty your pond. If you use a siphon, you will not need an outlet but you will need an overflow like the one described in Items 103- 113.

115. A siphon is a simple tube that runs from the inside of the pond over the bank and lies on the ground outside the pond.

116. A siphon can be made of plastic or rubber tubing at least 3 centimetres in diameter.

Top of bank

117. The siphon must be long enough to reach from the deepest part of the pond, run over the top of the bank and down the outside of the bank. You will need a siphon about 8 metres long to reach over the top of the bank from the deep part to the outside.

118. When you are ready to empty your pond, put all of the siphon into the pond. It will fill with water. Be sure the tube is full of water from one end to the other. If the siphon is not full of water, it will not work.

Empty the pond

119. While the siphon is still in the water, close one end of the tube with a plug and leave the other end open.


120. Leave the open end of the siphon below the surface of the water. You can use stones to held the siphon under the water, but be sure that they are not so heavy that the water will be shut off.

121. Take the other end of the siphon, which is closed with the plug, over the top of the bank and put it on the ground outside the pond. If the ground on the outside of the pond is higher than the pond bottom at the deepest part, you will have to dig a ditch so that the end of the siphon on the outside of the pond will be lower than the end of the siphon in the pond. The ditch will also take the water away when you empty your pond.

Empty the pond

122. Now, take the plug out of the siphon. If the end on the outside is lower than the end in the pond and if the end in the pond is under water, water will start to flow through the tube and out of your pond.

Take the plug out of the siphon

123. If the end of the siphon in the pond comes to the surface, the water may stop flowing. If this happens, put the siphon into the pond to fill it with water and begin again.

124. It will take a lot more time to empty a pond with a siphon than with an outlet. It you use a siphon of about 3 centimetres in diameter, it will take about three days to empty your pond.