| First of all Luke I'm talking about ponds deeper then 6 feet. I agree that 6 feet would be optimal (or 6.4 feet/2m). However when you go say 8 feet or 10 feet and shut down your pump for winter you will get thermal layers. The warmer water will be found at the bottom as the warmer earth below the frost line will keep it at a higher temperature. So now say you go out to your pond in the middle of winter and decide you want to get rid of some ice or because you read on the internet to run your pump all winter. Your pump that turns your pond over once an hour has now disrupted that layer and caused a significant temperature drop at the bottom where all the koi are. It makes sense to me that dropping water from say 39 to 36/37 in an hour would not be a good idea.
If the pond were heated then the pump would be running and I doubt you would have thermal layer problems.
__________________ Koi-Unit |