I installed the fountain and put the koi in the cages 3 months ago with no lost koi till yesterday when I added the sprayer bar from my well and lost 2 fish within 24 hours. The sprayer bar was at 100% pressure (1-1/4"pvc) so I reduced it to 50% and opened up the ball valve to spray the other 50% well water into the lake since I need to fill the pond. I also have a large aerator stone in each cage to help move water within the cages.
I also seen a bream with bulging eyes today swimming on top of the water, which I never seen that before?
Could adding the well water or high power sprayer bar cause any problems?