FROG® Serene Bromine Cartridge (Yellow) | Spa Refill
The FROG® Serene Bromine Cartridge is the consumable yellow cartridge for FROG's bromine-based Serene system — designed for hot tub owners who want the cleaner, gentler water of a mineral-and-bromine program without the daily fussing of traditional bromine dosing. Each 150g cartridge lasts 2 to 4 weeks depending on spa size and use, releasing bromine at the rate you set with the adjustable dial.
This is the standard single-cartridge refill — what you reorder when your current Serene bromine cartridge is depleted. It works in two different setups: the FROG Serene Floating System (a floating dispenser that drifts around your spa), and the FROG In-Line System that comes factory-installed on many hot tub brands. The cartridge is identical for both — what differs is just where the cartridge sits in your spa setup.
The Serene system pairs this yellow bromine cartridge with a separate blue mineral cartridge. Together they sanitize two ways: minerals as a first line of defense against bacteria, plus a low, steady level of bromine handling the rest of the work. That layered approach is what lets the Serene system use up to 50% less bromine than traditional bromine-only programs — gentler water, less smell, and far less wear on swimwear and skin.
FROG®
FROG® Brand FAQs
What makes FROG® different from regular chlorine or bromine?
FROG uses minerals as a first line of defense, which lets it sanitize with a much lower level of chlorine or bromine than traditional systems. Minerals and sanitizer work together to keep water clean two ways at once. The payoff for you is water that feels softer, has little to no chemical smell, and takes far less hands-on maintenance.
What is "Fresh Mineral Water®"?
It's FROG's term for the water its systems create: cleaner, clearer, softer, and easier to maintain. The minerals condition the water and help hold pH steady, while the reduced sanitizer level handles the rest — so you get sparkling water that's gentler on skin, hair, and swimwear than heavily chlorinated water.
Do FROG® cartridges really reduce how much chlorine I use?
Yes. Because the minerals do part of the sanitizing work, FROG® systems need significantly less chlorine or bromine to keep water clean. The @ease line with SmartChlor® Technology, for example, can use a fraction of the chlorine of a conventional hot tub program while still keeping the water properly sanitized.
How do the pre-filled cartridges work?
Each FROG® cartridge comes pre-filled with the right mineral or sanitizer formula — there's nothing to measure or mix. You simply drop or snap the cartridge into its holder or dispenser, set it, and let it do the work as water circulates. When a cartridge is spent, you swap in a fresh one. That's the "no mess, no guess, no stress" approach
FROG® is known for.
Will FROG® products work with my pool, hot tub, or swim spa?
FROG® makes systems for all three, in sizes ranging from small hot tubs to large in-ground pools, so there's almost always a fit. Some products are model-specific (for example, @ease cartridges sized for particular spa brands), so it's worth confirming the right version for your equipment. If you're unsure which FROG® product matches your setup, reach out and we'll help you pin it down.
How often do I replace the cartridges, and do I still need to shock?
Replacement timing depends on the product and your usage — mineral cartridges generally last for months, while sanitizer cartridges are swapped more often (the system's indicator tells you when). You'll still add a periodic shock to keep water freshly oxidized, but typically far less often than a fully manual program requires. Always follow the schedule printed on your specific product's packaging.
About Frog®
For more than 25 years, FROG® has been making pool, hot tub, and swim spa care dramatically simpler — without asking owners to compromise on water quality. Made by King Technology, FROG built its reputation on one patented idea: combine the natural cleaning power of minerals with a low, steady level of sanitizer, so your water stays clean using far less chlorine or bromine than traditional methods.
The result is what FROG calls Fresh Mineral Water® — water that's cleaner because it fights bacteria two ways (minerals plus a low level of sanitizer), clearer because balanced minerals help hold pH steady, and softer because those same minerals condition the water for a gentler feel on your skin. And it's easier, because nearly everything comes in pre-filled, drop-in cartridges. No measuring, no mess, no guesswork.
That convenience-first philosophy runs through the entire FROG lineup — from the SmartChlor®-powered @ease systems for hot tubs and swim spas, to the bromine-based Serene line, to the POOL FROG and Flippin' FROG systems for pools of every size, plus a full range of support chemicals and problem-solvers. Whatever you're sanitizing, there's a FROG product sized for it, and they're all built around the same goal: less time on maintenance, more time enjoying the water.
