Woke up to three dead koi out of seven. Any clues?
I have a 2000 gallon backyard pond. I had nine koi that I bought four years ago from a man who lived part time in Japan. They were maybe 8-10 inches when I got them (if that). I lost two the first year (can't remember why). Since then, they've been faring great and got really huge. Each one was a different coloring and type of koi and I loved all of the greedy buggers.
We had a MASSIVE thunderstorm yesterday (MI/USA). Power went out for a minute, but I didn't reset the waterfall due to the rain and the fact I wanted to clean the filters today. When I went out this morning, three of my koi were at the bottom of the pond. Two them were around the pump, which is under my potted reeds. One was on the other side.
They don't show any stress on their bodies. The water is fine, except the pH seems high-ish +7.6 (our tap water seems to be same), and KH (from that test strip) was low ~40ppm. I'm going to the pond store as soon as they open, but does anyone have any thoughts as to what happened? I'm extremely sad and now I'm worried about my other guys.
EDIT: I'm glad I posted on this sub. According to my local pond store, y'all are 100% correct. They said that I'm not the only one who has had issues. So I'm buying a solar aerator with a back up battery, installing a shade sail over the pond and aggressively adding algae fix to combat the unwanted plants. I'm so very sad that I lost Oliver (of Stan and Ollie), Groucho and Chico. They were friendly fish who liked to be pet (or didn't seem to mind, anyway).