Non-chiller tubs: the simple routine
If you're using a Cold Pod, Ice Barrel, or any tub without built-in filtration, water management is straightforward: fill, use, treat, and change regularly.
After each session: Add 1/4 cup of 3% hydrogen peroxide per 100 gallons. It's cheap ($3 at any drugstore), breaks down into water and oxygen, and kills bacteria without leaving chemical residue on your skin. Alternatively, use 1-2 tablespoons of bromine granules.
Every 3-7 days: Drain and refill with fresh water. In hot weather or with daily use, lean toward 3 days. In cold weather with occasional use, 7 days is fine. If the water looks cloudy or smells off, change it immediately regardless of schedule.
Weekly: Wipe down the interior walls with a mild cleaning solution. Rinse thoroughly before refilling.
Chiller tubs: leverage the filtration
Tubs like the Plunge and Arctic Warriors have built-in circulation and filtration systems. These are game-changers for water longevity. Clean, treated water being circulated and filtered can last 2-4 weeks without a full change.
The Plunge's ozone system is particularly effective. Ozone kills 99.9% of bacteria on contact and breaks down naturally, leaving no chemical taste or smell. If your tub has ozone, you need minimal additional treatment.
For chiller tubs without ozone: maintain a small residual sanitizer level. Bromine works better than chlorine in cold water because chlorine becomes less effective below 60°F. Test strips ($8 for 100) let you check levels in seconds.
The cover is your best friend
Using a cover when your tub isn't in use prevents 80% of maintenance headaches. It keeps out debris, insects, dust, and UV light (which breeds algae). It also retains cold, saving you ice or chiller energy.
If your tub didn't come with a cover, buy one or improvise. A foam insulation board cut to size works surprisingly well. Even a tarp secured with bungee cords is better than nothing.
Monthly deep clean
Once a month, drain the tub completely and do a thorough cleaning. Use a solution of white vinegar and water (1:4 ratio) or a mild non-abrasive cleaner. Scrub all interior surfaces, paying attention to the waterline where biofilm accumulates. Rinse thoroughly (multiple times) before refilling.
For chiller tubs: clean or replace the filter per manufacturer instructions (typically every 1-3 months). Run a line flush product through the plumbing quarterly to prevent biofilm buildup inside the pipes.
What not to do
Don't use bleach in large amounts. It's harsh on skin and degrades many tub materials. Don't use pool chlorine tablets designed for 10,000+ gallon pools in your 100-gallon tub. The concentration will be way too high. Don't add essential oils or bath products to shared cold plunge water. They clog filters and create biofilm. And don't ignore cloudy water or odd smells. When in doubt, drain and refill. Fresh water is cheap.