Okay, so I was SUPER nervous about my koi pond freezing over this winter. After reading tons of reviews, I took a chance on the Laguna PowerHeat 500W heater. Here's the real tea:

First off - this thing WORKED. Like, almost too well? We had temps down to single digits (°F!) and my entire pond stayed ice-free. My fish were chilling (literally) at the bottom but totally active when it warmed up a bit.

The red/green light situation is confusing AF though. Mine stayed red like 99% of the time which had me paranoid it was broken. But no - turns out that's normal? Laguna really needs to explain this better.

After 3 winters, it's still going strong! Though fair warning - some reviewers had leaks or shorts after shorter use. Mine's been solid though (fingers crossed).

Pro tip: Use a GFI outlet! Saw multiple reviews where this saved people from potential disasters.

Final verdict? If you want a set-it-and-forget-it solution that actually keeps your fish alive through brutal winters, this gets the job done. Just don't expect energy efficiency - it heats more than necessary but hey, alive fish > saving $20 on electricity.