Adding cold water bacteria strain

[waynefrcan]

My pond was at 35f for most of the winter with no circulation, just the pond breather.
All the fish seemed to survive.

I wish I could winter them outside, but it's hard on the koi even in the best setups. Every year I did it I lost the bigger koi and that's doing everything right. Also the skimmer boxes cracked after 4 years. That's when I found out they can't withstand our winters.