FROG Serene® In-Line System (formerly SPA FROG)

Built-in Hot Tub Care Sanitizer creates Fresh Mineral Water

Average Rating: 5 11 Reviews

Our FROG Serene System is so popular, some spa brands have built it directly into their spas. It makes hot tub care even easier, and your hot tub experience even more luxurious. With FROG Serene, there’s no measuring out the right amount or constantly adding chemicals.  You simply replace your FROG Serene cartridges when used up and enjoy weeks of Fresh Mineral Water®.  That’s what FROG Serene provides with minerals and a low level of bromine that makes water feel softer and look crystal clear.

Pool Foreground Hot Tub Foreground
50% Less

Lower your bromine use up to 50%* with FROG minerals

Bromine Disolves

Unlike chlorine, bromine slowly dissolves in hot water so it’s easier to regulate. Plus far less odors.

Icon 50% Less

Bromine is less impacted by pH swings ensuring sanitizing effectiveness

Soft Feeling

Soft feeling water that’s easier on skin, swimsuits and spa surfaces

Set and Forget

Just set it and forget it for weeks at a time

Money Back Guarantee

Money back guarantee

Serene On Towel

Video Introduction to FROG Serene In-Line System

Serene Cartridges

Additional Information

The FROG Serene Fresh Mineral Water In-Line System is part of the hot tub’s plumbing, with an easily distinguishable and convenient cap for top loading of the mineral and bromine cartridges. A simple twist and the cartridge basket is removed from the hot tub for quick and easy cartridge replacement. The entire process takes less than a minute. The minerals last a full four months set wide open, while the bromine usually lasts around three weeks with adjustable settings to meet each hot tub’s needs.

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What size hot tub will FROG Serene work in?

Hot tubs 150 to 600 are perfect for FROG Serene.

How does FROG Serene compare to other bromine floaters or using chlorine?

If you are tired of smelly chlorine odors and having to spoon in chemicals every time you use your hot tub, FROG Serene is for you. FROG Serene is not just bromine.  It contains FROG minerals that destroy bacteria so you need up to 50% less bromine. Plus with the In-Line System everything is tucked away but with easy access when you need it.

How long do the mineral and bromine cartridges last?

The mineral cartridge lasts four months or whenever the hot tub is drained and refilled. The bromine cartridge lasts 2-4 weeks.

Which hot tub brands have the FROG Serene In-Line System?

Marquis Spas, Caldera Spas and Hot Springs Spas all have the in-line system installed on select hot tub models at their factory.

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* Compared to the minimum ANSI recommended bromine or chlorine level of 2.0 ppm for a hot tub

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See Our Customer Reviews

  1. Ed Boinest

    Rating: 5

    We spend more time having fun than worrying about our water! The Frog System is absolutely remarkable.

  2. Madeline

    There doesn’t seem to be a way to determine if the cartridge needs to be replaced or not other than when your water starts getting cloudy. I like that it’s out of the way. I really hate throwing away so much plastic though. Please make them refillable!

  3. debbie morgan

    Rating: 5

    like the bromine better than chlorine, very easy to use but don’t see chemicals for sale on ur website.dou sell chemicals

  4. Gina Loshe

    We use the bromine/mineral cartridges in our hot tub!!😎🐸🌟😎🐸🌟 Love it!!

  5. Susan Kliewer

    Rating: 5

    I too had a really hard time trying to open the handle / screwtop this morning. I called the local dealer and they were helpful, but after many attempts, I broke one side of the handle where it is attached to the covering. I didn’t see the warning about the silicone lub on the O ring until this morning. I have been opening and checking and replacing the cartridges since I purchased my spa this summer. Is it possible to get a replacement handle /top. Also I need advice on how to get the “broken” handle / top off. I also need some of the lub please. Susan Kliewer 206 715 2380

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