| Usually the results of cold water are known in the spring when the koi begin to get active with the wamer temperatures. There can be all kind of issues, that have to do with something akin to frostbite, the seriousness of which can depend on cleanliness of the pond, parasite levels, previous sores or injuries. One year you may go thru just fine another year something could happen that would give you different results.
in a perfect world a chilling tower effect of a waterfall would be plumbed to be able to turn off or on with a recirculating pipe that bypasses it in winter.
That way you run your pipes with no concern of freezing up and you buy back a few warmer degrees. Well worth the effort to do after the fact. |