On Tue, 1 Oct 2013 11:34:22 +0100, Sacha
wrote:

On 2013-10-01 11:03:59 +0100, Jeff Layman said:

On 01/10/2013 10:39, Sacha wrote:
Oh dear, our two largest fish have died. Each was well over 1' long.
The pond pump has broken and another is on its way but we think it must
be lack of oxygen that's caused it. Ray played a hose over the pond
for a long time but obviously, it wasn't enough. It seems daft to be
upset about two dead fish but they used to give children such a thrill
when they glided up to be fed.

...to say nothing of what fish that size would cost to replace. How
big is the pond? Have the fish perhaps outgrown it, and the oxygen
levels fallen below what they require? It's usually stated to be about
1 square foot of surface area for each inch of fish.

All you wanted to know about pond aeration (and a lot more you didn't!):
http://www.fao.org/docrep/x5744e/x5744e0m.htm

20'x20'x4' But it's got a lot of fish in it and they've obviously
been breeding, which aiui is supposed to show that they're happy with
their conditions. We have never had this problem before so the failure
of the pump has to be the cause, I would be pretty certain.

If you want a pump of X litres per hour get two of X/2 litres per
hour. They can be plumbed together with plastic piping. Don't rely on
one pump.

Steve

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