(169) 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.
(170) You can use an overflow to keep the water in your pond from
rising over the banks.
(171) The better outlets you learned about in items 107 to 119
will act as an overflow.
(172) It you use a straight pipe outlet or a siphon
to let water out of your pond, you will need another kind of overflow.
(173) 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.
(174) 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.
(175) If you cannot get a pipe that is long enough, join short
pieces of pipe or bamboo together (see items 100 and 101).