a SaunaShare companyMatch water care to the equipment. Follow the instructions for your exact tub, chiller and treatment product. A method described for a simple ice bath may be unsuitable for a powered system. Never mix treatment chemicals.
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Quick answer
Yes, if your plunge's manual allows it, and some don't: Icetubs prohibits chlorine and bromine outright. Use a dichlor granule labeled for spas, keep free chlorine at 2 to 4 ppm and pH at 7.2 to 7.8 (7.4 to 7.6 is better), and test every 2 to 3 days. With Leisure Time Spa 56, that works out to about ½ teaspoon per 100 gallons whenever the strip reads under 2 ppm. Never add chlorine to water treated with hydrogen peroxide or a biguanide sanitizer. Expect it to work slower than in a hot tub: at 41°F, chlorine needs about four times the contact time it needs at 77°F.
Three rules before the first scoop.
- Your manual wins. Some makers ban chlorine outright, citing damage to their steel and their warranty terms. The list is below.
- Use a product labeled for spas or hot tubs. Spa chlorine is an EPA-registered product (Leisure Time calls Spa 56 an EPA-approved sanitizer), and EPA's rule for registered products is blunt: "the label is the law." If the label doesn't cover spas, it isn't meant for a small tub you sit in.
- One sanitizer at a time. Chlorine doesn't share a tub with hydrogen peroxide or biguanide. Switching systems means draining, not overlapping.
The numbers.
Health agencies write chlorine rules for public hot tubs. San Francisco is one of the few that has written them for cold plunges, aimed at businesses. Here's what each source says.
Free chlorine, bromine and pH targets by source
| Source | Free chlorine | Bromine | pH |
|---|---|---|---|
| CDC, public hot tubs | 3 ppm minimum | 4 ppm minimum | 7.0 to 7.8 |
| CDC, Legionella control for display hot tubs | 3 to 10 ppm | 4 to 8 ppm | 7.2 to 7.8 |
| San Francisco DPH, cold plunges at businesses | 3 to 10 ppm | 4 ppm minimum | 7.2 to 7.8 |
| Kohler x Remedy Place Ice Bath manual | 2 to 4 ppm | Not listed | 7.4 to 7.6 |
| Leisure Time residential spa labels | 2 to 3 ppm (Spa 56) | 2 to 4 ppm (Brom Tabs) | 7.2 to 7.8 |
For a plunge at home, 2 to 4 ppm free chlorine is the working range. It's what Kohler specifies for its own ice bath, and it overlaps the spa label. If other people use your plunge, run it at 3 ppm or higher, the floor CDC sets for public tubs. Washington's pool code caps disinfectant at 10 ppm and at the equipment maker's limit, whichever is lower.
Read free chlorine, not total chlorine. CDC says the sharp "chlorine" smell people notice is usually chloramines, which form when chlorine reacts with sweat and dirt, and which can irritate eyes and lungs.
Cold water slows chlorine down.
EPA's drinking-water disinfection tables give the contact time chlorine needs to kill a hard target at different temperatures. The absolute minutes are for Giardia cysts, a hardy parasite; common bacteria die far faster. The ratio is the point.
Minutes at 1 ppm free chlorine, pH 7.5, to kill 99.9% of Giardia cysts (EPA 1989 guidance tables)
| Water temperature | Contact time needed | Compared with 77°F |
|---|---|---|
| 77°F (25°C) | 45 minutes | 1x |
| 50°F (10°C) | 134 minutes | About 3x |
| 41°F (5°C) | 179 minutes | About 4x |
| 33°F (0.5°C) | 253 minutes | About 5.6x |
What that means in practice:
- Keep a steady residual. A splash right before you get in has less time to work in 41°F water than it would in a hot tub. Keep the level in range between plunges instead.
- Keep pH in the lower half of the range. At 41°F the same table needs 149 minutes at pH 7.0 against 179 at pH 7.5. Don't go below 7.2, the floor on every chart above.
- Hot-and-cold tubs change the rules. When an IceBarrel, SoulCold or Kohler runs on its heat setting, it's a hot tub, and the CDC hot tub numbers apply in full.
Check your plunge's manual first.
- Icetubs (IceBarrel, IceBath): The July 2026 operating manual says never use chlorine, acids, salts or bromine, because they damage the stainless steel and void the warranty. Its built-in ozonator plus weekly AquaFinesse is the only approved treatment. Owners can get Icetubs AquaFinesse at Sauna Marketplace.
- Kohler x Remedy Place Ice Bath: The homeowner's guide lists free active chlorine of 2 to 4 ppm and pH of 7.4 to 7.6 alongside its built-in UV. If you use a non-chlorine sanitizer instead, Kohler says to follow that product's instructions.
- SaunaLife S1: The tub manual rules out chlorine-containing cleaning agents on the tub because they discolor it, and sends you to the chiller maker's manual for the rest. That's reason enough to ask SaunaLife before you chlorinate the water.
- Finnmark SoulCold: The manual doesn't name a sanitizer, and the warranty excludes damage from failing to maintain proper water chemistry. Ask Finnmark which sanitizer it accepts for your unit, and keep the answer in writing.
- Everything else: Search the manual for "chlorine," "bromine," "chemical" and "warranty." If it's silent, ask the maker before the first dose, not after a leak.
Granules, tablets or a floater.
Dichlor granules: the right default.
Spa dichlor dissolves fast and lets you dose exactly what the strip says you're missing, which matters in 100 gallons. Leisure Time lists Spa 56 as 99% sodium dichloro-s-triazinetrione dihydrate with 55% available chlorine (55% on Leisure Time's own page, despite the name). The catch is that dichlor is stabilized: each molecule carries cyanuric acid. By the chemistry, every 1 ppm of chlorine it adds brings about 0.9 ppm of cyanuric acid with it.
Trichlor tablets: pool chemistry.
The 3-inch tablets sold for pools are trichlor: about 90% available chlorine, made to dissolve slowly into thousands of gallons. In a 100-gallon plunge, one tablet is a lot of chlorine you can't take back out. Trichlor also adds about 0.6 ppm of cyanuric acid per 1 ppm of chlorine. If the label doesn't give spa or hot tub directions, leave it for the pool.
Floating dispensers: hands-off, not precise.
A floater releases chlorine or bromine continuously, at a rate you set with a dial and then confirm with a strip. That works for bromine tablets, which are made for it. It's harder to dial in with chlorine in a small tub. Either way, lift the floater out before you get in.
Liquid chlorine: no stabilizer.
Spa-labeled liquid chlorine (sodium hypochlorite) adds no cyanuric acid. It's alkaline, so it pushes pH up as you dose. It suits people who chlorinate heavily and want to avoid cyanuric acid buildup.
How much chlorine for your plunge.
Leisure Time's Spa 56 label: add ½ ounce per 500 gallons when the residual drops below 2 ppm, and 1 ounce per 500 gallons to superchlorinate every 2 to 4 weeks. Scaled to plunge sizes below. Leisure Time's SpaPure dichlor label equates ½ ounce with about 1 tablespoon, which is the conversion used for the teaspoon column. A kitchen scale that reads to 0.1 gram is more accurate.
Leisure Time Spa 56 (55% available chlorine) doses scaled from the label's per-500-gallon rate
| Tub volume | Maintenance dose (under 2 ppm) | Superchlorinate (every 2 to 4 weeks) |
|---|---|---|
| 50 gallons | 0.05 oz (1.4 g), about ¼ tsp | 0.10 oz (2.8 g), about ½ tsp |
| 80 gallons | 0.08 oz (2.3 g), about ½ tsp | 0.16 oz (4.5 g), about 1 tsp |
| 100 gallons | 0.10 oz (2.8 g), a heaping ½ tsp | 0.20 oz (5.7 g), about 1¼ tsp |
| 125 gallons | 0.125 oz (3.5 g), about ¾ tsp | 0.25 oz (7.1 g), about 1½ tsp |
| 150 gallons | 0.15 oz (4.3 g), a scant 1 tsp | 0.30 oz (8.5 g), about 1¾ tsp |
| 200 gallons | 0.20 oz (5.7 g), about 1¼ tsp | 0.40 oz (11.3 g), about 2½ tsp |
On paper, the maintenance dose adds about 4 ppm of available chlorine at any volume; the label expects some of it to be used up and aims for 2 to 3 ppm. Before the first dose on a fresh fill, the label says to bring pH to 7.2 to 7.8 and total alkalinity to 80 to 120 ppm. Broadcast the granules across the surface with the pump running, wait at least 5 minutes, then retest.
After a superchlorination dose, leave the cover off and stay out until free chlorine falls back to 2 to 3 ppm, per the label.
One warning about the Amazon page for the 2 lb bucket: its auto-generated "Directions" summary says 1 lb per 500 gallons. Leisure Time's own label says ½ ounce. Dose from the label.
Watch the cyanuric acid.
Run the math on a typical month: twice-weekly maintenance doses plus one shock is the chlorine of ten maintenance doses, and with dichlor that adds roughly 37 ppm of cyanuric acid by itself. CDC's Legionella guidance says stabilized chlorine shouldn't be used in hot tubs at all because it slows disinfection, and cold water already slows it. Washington's pool code caps cyanuric acid at 90 ppm for public pools.
The fix is built into a small tub: every drain resets cyanuric acid to whatever your tap water has, usually none. Watch the CYA pad on your strip, drain on schedule (the water care guide has the schedule by tub size), and switch to spa-labeled liquid chlorine if you find yourself dosing every day.
Bromine works too, with a slower start.
Bromine does the same job and is judged by the same agencies: CDC sets a 4 ppm minimum for public hot tubs, and San Francisco uses the same floor for business plunges. Leisure Time's directions for its Dantabrom bromine tablets call for 2 to 4 ppm in a residential spa (3 to 6 commercial).
- Start with a bromide reserve. On a fresh fill, Leisure Time adds ½ ounce of sodium bromide per 100 gallons before the tablets go in.
- Tablets go in a floater, never loose. Leisure Time says not to add tablets directly to spa water. Start the floater at its middle setting, then raise or lower it based on what the strip reads.
- It's not chlorine-free. Dantabrom is a bromochloro-dimethylhydantoin, so the tablets carry chlorine too. Any maker that bans chlorine and bromine, as Icetubs does, bans these.
- Same never-mix list. Leisure Time warns against combining the dry tablets with chlorine products, biguanide or oxidizers.
Never mix these.
- Chlorine and hydrogen peroxide. Peroxide is a dechlorinating agent; EPA lists it among the chemicals used to remove chlorine from wastewater. Combine them and you end up with less of both. Switching from peroxide to chlorine means a fresh fill.
- Chlorine and biguanide (PHMB). Leisure Time's label: chlorine "cannot be combined with biguanide chemistry under any circumstances." Baqua Spa and SoftSoak are biguanide brands.
- Dry chlorine and other chemicals, in the container or the scoop. The label lists other chlorine products, bromine, biguanide and oxidizers, and warns that concentrated mixing can cause violent reactions or fire. Add each product directly to the tub water, one at a time.
Skin, eyes and the smell.
Most of the irritation people blame on chlorine comes from chloramines. CDC lists red, itchy eyes, skin irritation and rashes among their effects, and says the "chlorine" smell at a pool is usually chloramines, not chlorine. Three habits keep them down: shower for a minute before every plunge (CDC says that removes most of the sweat, dirt and oils that use up chlorine), keep free chlorine in range rather than spiking it, and don't get in after a shock until the strip is back to 2 to 3 ppm. If your skin still reacts at normal levels, chlorine may not be the sanitizer for you; the water care guide compares the alternatives, including hydrogen peroxide.
Safety: Store chlorine and bromine in their original, tightly closed containers in a cool, dry, ventilated spot out of direct sunlight. CDC says to keep pool chemicals below 95°F, store incompatible chemicals away from each other, and secure the storage area from children and animals. Leisure Time adds that dry chlorine should be stored separately from acids, oxidizers and organic materials, and that granules left open absorb moisture and degrade. Use a clean, dry scoop for each product.
What to buy.
Four products cover a chlorine or bromine plunge. For a peroxide setup, use the picks on the water care guide instead.
Best for most chlorine plunges
Leisure Time 22337A Spa 56 Chlorinating Granules, 2 lbs
- Active: sodium dichloro-s-triazinetrione dihydrate, 99%
- Available chlorine: 55%, per Leisure Time
- Label dose: ½ oz per 500 gallons to hold 2 to 3 ppm
- Works alongside: ozone systems and mineral cartridges, per Leisure Time
Dichlor made for spas, with a label that gives an exact dose, a test interval and a shock schedule. At about 0.1 oz per maintenance dose in 100 gallons, a 2 lb bucket holds roughly 320 doses, so the small size is plenty; Leisure Time warns that open granules absorb moisture and degrade, which argues against buying the 5 lb bucket for one plunge.
Skip it if: your tub's maker prohibits chlorine (Icetubs does), you use peroxide or a biguanide sanitizer, or you chlorinate daily and want to avoid cyanuric acid buildup.
Best for reading chlorine, pH and CYA
JNW Direct Pool Test Strips, 7 in 1, 100 Pack
- Reads: free chlorine, bromine, pH, alkalinity, hardness and cyanuric acid
- Count: 100 strips
- Read time: dip 2 seconds, read at 30 seconds
- Shelf life: use within 90 days of opening, per JNW
The cyanuric acid pad is the reason to pick this over a 3-way strip: it's how you see dichlor building up before it slows your chlorine down. Free chlorine and bromine have separate pads, so it works for either system.
Skip it if: you sanitize with hydrogen peroxide; it has no peroxide pad.
Best for bromine plunges
Leisure Time 45425A Brominating Tablets, 1-1/2 Pound
- Chemistry: Dantabrom (bromochloro-dimethylhydantoin)
- Size: 24 oz of tablets
- Target: 2 to 4 ppm bromine for residential spas, per Leisure Time
- Feeder: fits all floaters, per the listing
Tablets in a floater trickle bromine out continuously, so there's no scoop to measure twice a week. The listing describes them as low-odor and low-dust. Start with sodium bromide on a fresh fill, as the directions say, and adjust the floater by test.
Skip it if: your maker bans bromine or chlorine (these tablets contain both), or you want to fix a low reading in five minutes; a floater changes the level slowly.
Best for holding bromine tablets
U.S. Pool Supply Floating Spa, Hot Tub and Small Pool Chemical Dispenser
- Holds: 1-inch chlorine or bromine tablets
- Settings: 6 flow levels, set by twisting the top
- Build: weighted body, tie string included
- Made for: spas, hot tubs and small pools
A spa-size floater sized for 1-inch tablets, which is what a plunge needs. The tie string lets you tether it to one side so it doesn't drift into your lap, and the six settings give you room to turn output down for a small tub.
Skip it if: you use dichlor granules; a floater is for tablets. Lift it out before every plunge.
FAQ
Can you put chlorine in a cold plunge?
Yes, if the manual allows it. Kohler lists 2 to 4 ppm free chlorine for its ice bath; Icetubs prohibits chlorine and bromine because they damage its stainless steel and void the warranty.
How much chlorine do I put in my ice bath?
Enough to hold 2 to 4 ppm free chlorine. With Leisure Time Spa 56, the label rate works out to about 0.1 oz (a heaping ½ teaspoon) per 100 gallons when the strip reads under 2 ppm.
Can I use chlorine tablets in my ice bath?
Not 3-inch pool trichlor tablets: they're made for thousands of gallons and add cyanuric acid. Use spa-labeled dichlor granules, or bromine tablets in a floater if your tub's maker allows bromine.
Should I use chlorine or hydrogen peroxide?
Chlorine has public-health targets and a test pad on every strip; 3% peroxide is simpler to handle and leaves no stabilizer behind. Pick one and stay with it, because peroxide destroys chlorine. Our peroxide guide covers that side.
Can I use bromine in an ice bath?
Yes, if your maker allows it. Leisure Time's residential target is 2 to 4 ppm, CDC's public hot tub floor is 4 ppm, and the tablets belong in a floater, not loose in the tub.
Does chlorine work in cold water?
Yes, but slower. EPA's tables show it needs about four times the contact time at 41°F that it needs at 77°F, so keep a steady residual instead of dosing right before you get in.
How long after adding chlorine can I get in?
After a maintenance dose, the label says to circulate at least 5 minutes and retest. After a shock, stay out with the cover off until free chlorine reads 2 to 3 ppm again.
Can I use household bleach?
Only if its label gives directions for spas or hot tubs. Otherwise use a spa-labeled product; EPA's rule for registered products is that the label is the law.