Question
I have a pond about two feet deep and 15 by 10feet. I have a waterfall. I have been told to turn off my waterfall in the winter because the koi need undisturbed water in the winter.  I was told that the bottom layer of water needs to be still to maintain a warmer temperature.  I was also told to keep the waterfall one all winter by someone else! What do I do?  I want my koi to survive the cold weather!

Answer
Where do you live?  My pond is about 15 x 20 feet and only 26" deep in Zone 6/7.  I leave my waterfall going all winter but it's been tricky a few times.  I go over winterizing and whether or not to turn off pumps and waterfalls at http://www.fishpondinfo.com/winter.htm which should clear some things up.  If the waterfall is such that it will divert or cause other problems in the winter, you want to turn it off.  Otherwise, the aeration and water movement that it provides is good.  A 2 foot pond is not deep enough for much of a warm layer to ever form in the bottom of it.  Those little warmer layers on the bottom are only tenths of a degree warmer and tend to be low in oxygen.  That's where the koi are resting so low oxygen is bad.  Good luck!

Robyn