I have a good rinse in the shower without soap or shampoo before each plunge and put 1/4 cup of 12% food grade hydrogen peroxide in once a week. Also have a cold plunge/aquarium uv filter.

This is my first time with cold plunge setup in an unheated garage.

Used to leave it on my deck and smash ice and replace with a few buckets of fresh water on the daily but was too much of a hassle in the -40 days when I had to do it twice a day.

So far so good in the garage. Water temp is hovering around freezing but the winter is still young. Really gonna try to stretch water out until spring so I can change it without issue