Description
The Yellow Bromine Refill That Keeps Your FROG Serene Floater Working
The Spa Frog Serene Bromine Cartridge is the yellow 150 g bromine refill for the FROG Serene Floating and In-Line systems. It sits beside the blue mineral cartridge in the floater or the built-in holder and releases a steady, adjustable dose of bromine, so there is nothing to measure or pour.
Each cartridge typically lasts 2 to 4 weeks. When the bromine runs out, drop in a fresh one, set it to your hot tub size and keep soaking.
Prefilled Bromine, No Measuring
The bromine is sealed inside the cartridge, so you never scoop tablets or handle loose chemicals. Set the dial once and the cartridge feeds bromine into the water as it floats.
Works With FROG Minerals for Lower Bromine
Paired with the blue FROG Serene Mineral Cartridge, the system holds a bromine level of 1.0 to 2.0 ppm. FROG says that is up to 50% less bromine than the 2.0 ppm minimum in the ANSI standard for hot tubs, for water that feels softer and smells less like chemicals.
Dial It In to Your Hot Tub Size
Settings 0 through 6 match hot tubs from 200 to 600 gallons. If the reading runs high or low, turn the cartridge one number and retest the next day.
Easy to Tell Apart by Color
Yellow means the 150 g Serene bromine. That makes it simple to reorder the right refill instead of a blue mineral cartridge or a FROG @ease cartridge.
Key Features and Benefits
- 150 g Prefilled CartridgeYellow, 5.3 oz of bromine sealed inside.
- Floating or In-LineFits the Serene floater or a built-in Serene holder.
- Adjustable 0–6Matched to hot tubs of 200 to 600 gallons.
- 2–4 Week LifeReplace when empty.
- Pairs With FROG MineralsLower bromine level of 1.0–2.0 ppm.
- No MeasuringNothing to scoop or pour.
- EPA RegisteredEPA Reg. No. 53735-16.
Product Details
| Product Detail | Information |
|---|---|
| Brand | FROG (King Technology, Inc.) |
| Product | Spa Frog Serene Bromine Cartridge |
| Pack Size | 1 cartridge |
| Cartridge Size | 150 g (5.3 oz) net per cartridge |
| Total Contents | 150 g (5.3 oz) |
| Cartridge Color | Yellow |
| Product Type | Prefilled bromine sanitizer cartridge for hot tubs |
| Active Ingredient | BCDMH (1-bromo-3-chloro-5,5-dimethylhydantoin), 98.0% |
| Other Ingredients | 2.0% |
| Contents Form (SDS) | White tablets or granules sealed inside the cartridge |
| Made For | FROG Serene Floating System and FROG Serene In-Line System |
| Use With | FROG Serene Mineral Cartridge (blue), set to #6 |
| Hot Tub Size | About 200–600 gallons on the setting chart |
| Adjustable Settings | 0 to 6, matched to hot tub gallons |
| Target Bromine Level | 1.0–2.0 ppm, at least 1.0 ppm at all times |
| Water Balance (Floating Manual) | pH 7.2–7.6, total alkalinity 80–120 ppm, total hardness 150–250 ppm, TDS under 1,500, cyanuric acid 0–50 ppm |
| Typical Cartridge Life | About 2 to 4 weeks, depending on hot tub size and use |
| Refillable | No |
| Recommended Shock | FROG Maintain non-chlorine shock, weekly or as needed |
| Holder or Floater Included | No |
| Hazard Classification (SDS) | Danger: corrosive, causes severe skin burns and eye damage, harmful if swallowed or inhaled, may cause an allergic skin reaction, oxidizer |
| Storage | Original packaging, tightly closed and upright, cool and ventilated, at or below 86°F (30°C), locked up |
| Shipping Note (SDS) | Shipped under Limited Quantities provisions |
| EPA Registration No. | 53735-16 |
| California Registration No. | 53735-16-AA |
| Manufacturer Part Number | 01-14-3824 |
| Store SKU | 01-14-3824 |
| UPC | 722906038214 (single cartridge) |
| Estimated Supply | One cartridge, about 2 to 4 weeks |
| Image Alt Text | Yellow Spa Frog Serene 150 g bromine cartridge for FROG Serene Floating and In-Line systems, front label |
How to Use the FROG Serene Bromine Cartridge
- Balance the water first: Test with FROG Test Strips and adjust total alkalinity to 80–120 ppm, then pH to 7.2–7.6, then hardness to 150–250 ppm. Add one balancer at a time with the jets on and wait 6 hours before retesting.
- Start up with FROG Jump Start: After a fresh fill, set a starting level of 1.0–2.0 ppm with one Jump Start packet per 600 gallons. FROG says not to use a non-chlorine shock at start-up.
- Set both cartridges: Turn the blue mineral cartridge to #6. Turn the yellow bromine cartridge to the number on the setting chart for your hot tub's gallons.
- Snap them into the floater: Push both cartridges into the openings of the green FROG Serene Floating System holder until they stay in place, then let it float in the hot tub.
- Fine-tune for a week: Test daily for the first week and move the bromine cartridge up or down one number per day until the strip matches 1.0–2.0 ppm.
- Swap the yellow cartridge when empty: Replace it when it runs out, usually every 2 to 4 weeks. Drain the water out of the old one, then discard it or recycle it where available.
FROG Serene Bromine Cartridge Setting Chart
| Hot Tub Size | Bromine Cartridge Setting |
|---|---|
| 200 gallons | 0 |
| 250 gallons | 1 |
| 300 gallons | 1 |
| 350 gallons | 2 |
| 400 gallons | 3 |
| 450 gallons | 4 |
| 500 gallons | 5 |
| 550 gallons | 5 |
| 600 gallons | 6 |
From the FROG Serene Floating and In-Line manuals. The blue mineral cartridge always goes on #6. For the first week, test daily and move the bromine cartridge up or down one setting per day until the strip reads 1.0 to 2.0 ppm bromine.
Compatibility Notes
Before You Buy
- This is the yellow 150 g FROG Serene Bromine Cartridge. FROG's 2026 catalog lists it for both the FROG Serene Floating System and the FROG Serene In-Line System.
- In a built-in FROG Serene In-Line holder it goes in the bottom position, under the blue mineral. FROG also makes a larger green 200 g bromine cartridge, mainly for in-line holders. FROG Serene bromine cartridges of either size work in both the floater and in-line holders.
- It needs a blue FROG Serene Mineral Cartridge alongside it. FROG notes the lower bromine level only applies when FROG minerals are in use.
- Not for FROG @ease systems, which use SmartChlor chlorine cartridges instead of bromine.
- Sized for hot tubs from about 200 to 600 gallons on the setting chart. FROG's floating system page lists hot tubs of 150 to 600 gallons.
- The cartridge holder or floater is not included. This listing is the replacement cartridge only.
Which FROG Serene Cartridge Do I Need?
| Cartridge | Made For | Replace |
|---|---|---|
| FROG Serene Mineral Cartridge (blue) | Serene Floating and Serene In-Line | Every 4 months, or at each drain and refill |
| FROG Serene Bromine Cartridge, 150 g (yellow) (this listing) | Serene Floating and Serene In-Line | When empty, about every 2 to 4 weeks |
| FROG Serene In-Line Bromine Cartridge, 200 g (green) | Mainly Serene In-Line (also fits Floating) | When empty, about every 2 to 4 weeks |
| FROG Serene Cartridge Kit (1 blue + 3 yellow) | Serene Floating or In-Line refill | One mineral cycle plus three bromine changes |
| FROG Serene In-Line Refill (1 blue + 1 green) | Serene In-Line refill | One mineral cycle plus one bromine change |
| FROG @ease cartridges | FROG @ease systems only | Separate SmartChlor system, not interchangeable with Serene |
Colors help you tell them apart: blue is always the mineral, yellow is the 150 g bromine and green is the larger 200 g bromine, made mainly for in-line holders. Either bromine size fits both Serene systems.
How Long Each Pack Lasts
| Pack | One Hot Tub, One Cartridge at a Time |
|---|---|
| 1 cartridge (this listing) | 2–4 weeks |
| 3 Pack | About 6–12 weeks |
| 6 Pack | About 3–6 months |
| 12 Pack | About 6–11 months |
Based on FROG's 2 to 4 week cartridge life. Large hot tubs, frequent soaks and heavy bather loads empty cartridges sooner. Remember the blue mineral cartridge also needs replacing every 4 months.
Why Choose the Spa Frog Serene Bromine Cartridge
It is the genuine yellow refill FROG makes for both Serene systems, so the fit, the setting dial and the bromine output all match the floater or built-in holder and the mineral cartridge you already use. Shop the full FROG Serene line, or compare every hot tub bromine option at HotTubPirate.com.
Ideal For
- FROG Serene Floating and In-Line owners
- Hot tubs from 200 to 600 gallons
- Owners who want bromine without measuring
- Keeping one spare on the shelf
- Lower-bromine water with FROG minerals
Frequently Asked Questions
What color is the Spa Frog Serene bromine cartridge?
Yellow. The yellow one is the 150 g bromine cartridge that FROG lists for both Serene systems. The green one is the larger 200 g bromine cartridge, mainly used in in-line holders, and the blue one is the mineral cartridge.
How long does a Spa Frog bromine cartridge last?
FROG puts it at about 2 to 4 weeks. Larger hot tubs, more bathers and longer soaks empty it faster, while a lightly used hot tub can stretch toward the full four weeks.
Can I refill a FROG bromine cartridge with bromine tablets?
No. The label says the cartridge is not refillable and should not be refilled. It is designed to release its prefilled bromine at a set rate, and loose tablets would change that.
Will the yellow cartridge work in a FROG Serene In-Line system?
Yes. FROG's 2026 catalog lists the yellow 150 g cartridge for the Serene In-Line System as well as the floater. It goes in the bottom of the holder, under the blue mineral.
What setting should I use on the bromine cartridge?
Match your hot tub's gallons on the chart: 0 for 200, 1 for 250 to 300, 2 for 350, 3 for 400, 4 for 450, 5 for 500 to 550 and 6 for 600 gallons. Then fine-tune by test strip.
How do I know when the bromine cartridge is empty?
Bromine readings that keep slipping under 1.0 ppm at your usual setting are the first sign. FROG's manual says to check the cartridge and, when you replace it, drain the water out to confirm it is empty.
Do I need the mineral cartridge too?
Yes. The Serene system is built as a pair. FROG notes the lower bromine levels only apply when the blue FROG Serene Mineral Cartridge is in use with the bromine cartridge.
What is the active ingredient in the FROG Serene bromine cartridge?
BCDMH, short for 1-bromo-3-chloro-5,5-dimethylhydantoin, at 98.0%. It is a common hot tub bromine compound, sealed inside the cartridge as tablets or granules.
What should I do if my bromine level is too high?
FROG's manual says to take the floater out until the level drops to 2.0 ppm, lower the bromine cartridge one setting, put it back and test again in 24 hours. Repeat until it holds 1.0 to 2.0 ppm.
Should the floater stay in while we use the hot tub?
No. FROG says to remove the Serene floater before you soak, drain the water back into the hot tub and set it upside down on the side. Put it back in the water when you get out.
Is Spa Frog the same as FROG?
Yes. Spa Frog is the name many owners and dealers still use for FROG hot tub products. This cartridge is the FROG Serene bromine cartridge made by King Technology, order code 01-14-3824.
Which shock should I use with FROG Serene?
FROG Maintain, its non-chlorine shock, once a week or as needed. The Serene manual warns against dichlor shock because the cyanuric acid it builds up reduces the bromine cartridge's effectiveness.
What is the part number and UPC for this cartridge?
FROG's order code is 01-14-3824. The UPC on the single cartridge is 722906038214. You will also see it listed as the FROG Serene 150 g bromine cartridge.
What water balance does FROG Serene need?
The floating manual lists pH 7.2 to 7.6, total alkalinity 80 to 120 ppm, total hardness 150 to 250 ppm, total dissolved solids under 1,500 and cyanuric acid 0 to 50 ppm.
How do I throw away an empty cartridge?
Drain the water out of it first so it is fully empty, then put it in the trash or offer it for recycling where your area accepts it, as FROG's manual directs.
Safety Notes
Handle With Care
- Danger: corrosive. The bromine inside causes severe skin burns and eye damage and is harmful if swallowed or inhaled. Wear gloves and eye protection when you handle or drain a cartridge.
- Do not open, break or refill the cartridge, and do not handle a damaged cartridge without protective gear.
- Strong oxidizer. Keep it away from heat, flames and combustible materials, and never mix it with other chemicals.
- Do not use it in a feeder or other device that has been used with calcium hypochlorite.
- If it gets in the eyes, rinse cautiously with water for several minutes, remove contact lenses if easy to do, keep rinsing and call a poison center or doctor right away.
- Store cartridges in the original packaging, tightly closed and upright, in a cool, well-ventilated place at or below 86°F (30°C), locked up and away from children and pets.
Product Documents
Download the FROG Serene Floating System and In-Line System manuals for the setting chart and replacement steps, plus the official Safety Data Sheet for the bromine cartridge.