[simple10]

I built a DIY ice bath out of a large chest freezer. Big enough for me to fully submerge. Works like a charm. I use a large aquarium filter to circulate the water and an ozone generator to keep the water clean. With this setup, I rarely need to replace the water.

All it took was sealing up the inside of the freezer with silicone caulk to make it waterproof. Then drill a 2" hole in the freezer lid for the filter power cord and ozone generator hose. I put a PVC pipe gasket on the hole to seal it up and prevent any heat transfer. This also allows me to switch the freezer back to regular freezer mode if I no longer wanted to use it as an ice bath. According to my FLIR, there's no heat transfer when the hole is sealed. So the modification doesn't have any downside for future use as a regular freezer.

I use an Inkbird temperature controller outlet to regulate the temperature. The freezer is plugged into the controller. A temperature probe is inserted into the water. The controller will turn on and off the freezer to keep the desired temperature (45 degree F in my case).

Total cost is <$1,000 USD where a commercial ice bath is upwards of $10k. The only real difference between the two is the aesthetics and safety concerns. With a commercial ice bath, you can keep it plugged in. With a DIY ice bath, you need to unplug it whenever you're using it for safety reasons. Even with a GFCI, it's best to just unplug the whole thing when in use.

[fishbone]

I’m going to experiment with my setup some more, but I may go your route in the end.

[simple10]

Using the chest freezer as the tub is ideal because it's already insulated. It takes a couple days to get the water temperature down from room temperature to ice bath levels. But once it's cold, it stays cold. In my setup, the freezer only kicks in once or twice a day to keep the temperature at 45 degrees F.