You walked outside expecting to see your koi gliding through sparkling water. Instead, your pond looks like someone poured in a gallon of milk, blended up a bag of leaves, or replaced the water with pea soup.
Even worse, your koi may have vanished beneath the murk.
Cloudy koi pond water can appear suddenly, and it often sends pond owners into panic mode. The good news is that cloudy water is usually fixable. The bad news is that dumping in random chemicals, draining the pond, or aggressively cleaning the filter can make the problem much worse.