In message , Doghouse Riley
writes
The idea that there can be a layer of warmer water at the bottom of a
pool is a myth. It won't happen in normal koi pools of around five or
six feet in depth. You'd need to have something well in excess of 3
metres.
It' snot a myth - it's a scientific fact that the density of water
increases as it cools down to about 4 C then it decreases as the water
cools further. (Hope I've got that the right way round) In this respect
water is unique. That means in a natural pond the water at the bottom
will be at 4C with the colder water at the top until it is so cold that
the whole lot freezes.
However as you say disturbing this with pumps running will interrupt
this natural protective mechanism for pond life.
Isn't nature amazing.
--
hugh