6 Hot Tub Sanitizer Alternatives To Try (No Chlorine Or Bromine)



Staying healthy is a priority for many, so some hot tubbers prefer alternatives to traditional spa sanitation chemicals.

Chlorine or bromine are still the top choices for tubs due to their low cost and effectiveness against bacteria, viruses, and harmful pathogens, but these chemicals can still be reduced using additional sanitizers in a one-two punch combo.

Let’s explore what hot tub chemical alternatives you can use to keep the water clean, and whether or not they’re a good fit for you.

Why Look For Alternatives?

There are a few reasons why you should entertain the idea of using alternative chemical sanitizers.

  • The water feels better. Many people hate how dry their skin and hair feel after being exposed to chemical sanitizers like chlorine or bromine. When using an alternative chemical, these side effects are greatly reduced, and the water ends up with a more gentle and silky feel.
  • You’ll save money. Traditional chemicals like chlorine and bromine work 24/7, and need to be replenished regularly to keep the water clean. By using an alternative, you’ll use less traditional chemicals, which means you’ll buy less of them and ultimately save money.
  • The tub will smell better. When chlorine or bromine is used up by pollutants, it creates a gaseous by-product known as chloramines or bromamines, respectively. This gas is not only an irritant that can lead to itchy eyes, skin, and nasal passages, but it produces a pungent scent that isn’t produced by alternative chemicals.
  • It’s less harsh. Traditional chemicals can cause sensitivities in bathers. Many people experience irritant reactions such as rashes and itchy bumps on their skin. While it may look like an allergy, it’s actually a hypersensitivity to the chemical, and will only go away by rinsing the area with clean water or taking OTC medications.
  • Your swimwear lasts longer. Chlorine and bromine are bleaches. Even though they’re heavily diluted for safe bathing, this bleach can still eat through your swimwear, cutting short it’s lifespan. This is why you should always rinse your bathing suit after going for a dip in a tub or pool.

Can A Hot Tub Go Without Chemicals?

Well, you could, but you’d soon regret it. Using a hot tub without any sanitizing chemicals will quickly turn into a biohazard.

Hot tub chemical alternatives are meant to be used in conjunction with chlorine/bromine. While alternatives can help clean the water, their main job is to simply lend a helping hand. 

They tackle specific pollutants (mainly organic ones), so that chlorine/bromine doesn’t have to. This frees it up to focus on the more serious contaminants that must be eradicated – such as harmful viruses and bacteria.

Note: The one exception is Biguanide (see below), which does not require any chlorine/bromine.

Hot Tub Sanitizer Alternatives

Chlorine and bromine aren’t the only sanitizing options available for your hot tub, so let’s talk about the alternatives you can use.

1. Biguanide

Biguanide is a chlorine-free water cleaner that was originally used as a surgical disinfectant.

Where chlorine kills bacteria and microorganisms, biguanide binds them. These clumped up contaminants are then removed by the hot tub’s filter.

It’s important to note, however, that biguanide only works against bacteria. To get rid of organic pollutants, the water will require an oxidizer as well.

Biguanide goes by a few brand names (Baquacil, SoftSwim, Revacil, Aqua Silk) and is a multi-chemical system that must be used together for full effect. 


  • It’s stable. Biguanide won’t break down in sunlight, works well in high water temperatures, and won’t react with metals in the water.
  • It’s more gentle than chlorine or bromine, which can cause dry/itchy skin and eyes, as well as nasal and lung irritation in some people.
  • There’s no overpowering chlorine/bromine smell from the formation of chloramines/bromamines. In fact, biguanide has no smell at all.


  • It’s an expensive option that must be used with multiple products in their brand (usually an oxidizer, a clarifier, and an algaecide).

  • Biguanide is limited in what it can do and isn’t a full-spectrum sanitizer like chlorine. Over time, some microorganisms can even build up resistance to biguanide.
  • Bonded pollutants can get caught in the filter and cause cloudy water. You’ll need to clean the filter and add a clarifier to fix the issue.  

2. Ozonators

Ozonators can be installed in your hot tub’s equipment line, oxidizing and disinfecting the water at the same time.

The method works by generating ozone gas, and then injecting it into the water before it returns to the tub. The ozonator also gives your water a silky feel and is gentle on your body and swimwear.


  • Only requires 0.5 ppm chlorine and 1 ppm bromine, as opposed to the standard 1-3 ppm chlorine and 3-5ppm bromine without an ozonator.
  • Reduces your required shocking frequency, as they break up chlorine/bromine molecules that have bonded with pollutants.
  • Reduces total dissolved solids (TDS) by clumping them together, allowing the filter to remove them. This is helpful as TDS over 1500 ppm requires draining.


  • Ozone is highly reactive, and can cause corrosion throughout the tub and equipment. Before installing an ozonator, ensure the tub and filtration system are corrosion-resistant.
  • New tubs are equipped to handle an ozonator installation, but older models may have compatibility issues, especially where voltage is concerned.
  • To clean the tub, you’ll have to run it at least 4 hours a day, and up to 8 hours in some cases, shortening it’s 18 to 24 month lifespan.

3. Ionizers

Ionizers use minerals such as silver and copper to keep the tub clean.

Through electrolysis, they introduce a low voltage charge through a mineral electrode that’s installed in the filtration system’s return line.

This charge releases silver and copper ions to help eradicate mold, algae, viruses, and bacteria that may be present in the water.


  • With silver and copper being natural antibacterials, you’ll reduce chlorine/bromine by 80%.
  • You won’t have to shell out for an algaecide product, as the ions take care of algae blooms before they have a chance to start.
  • An ionizer is relatively inexpensive when you weigh it against the amount of chlorine/bromine you’d be using over the long-term.


  • High copper levels can turn your hot tub water green because copper turns green when it oxidizes (when mixed with chlorine or bromine).
  • Higher metal content in the water makes your tub more prone to staining, though using metal sequestrate can reduce this risk.
  • It doesn’t eliminate all microorganisms, so you’ll always need to maintain a level of chlorine or bromine in the water.

4. UV Systems

UV light can be harnessed to kill off tub contaminants as well.

It disinfects by using a high-intensity germicidal ray that alters the DNA/RNA of harmful organisms such as algae, protozoa, and bacteria. Organic matter also becomes inactivated when exposed to this light.

Despite it’s high-tech method of using ultraviolet radiation to scramble DNA/RNA, a UV system is safe for use with your tub. It’s installed in the filtration system’s piping and kills off pathogens within seconds after water passes through.


  • Changes the genetic makeup of pollutants in the tub, inactivating them so they can’t reproduce
  • Inactivation of pollutants is near instantaneous 
  • Is easy to install in the pipelines of your tub’s filtration system


  • UV light doesn’t kill anything in the tub. It’s also limited to a certain frequency, and if dust gets on the bulb it can disrupt its effectiveness.
  • UV systems can be very expensive. Entry level models can start around $150, but an average price is closer to $500, and high-end UV generators can be upwards of $1000.
  • UV light only works when water passes through it, and you’ll have to run the tub for hours at time so the water is fully “filtered” by the light.

5. Salt Systems

Salt water pools have gained in popularity for their gentle nature and ability to keep things clean. It makes sense that many spa owners are turning to salt systems for the same reasons.

This sanitation method requires a large dose of salt to be added to the water. Despite popular belief, these systems use a generator to convert salt to chlorine or bromine through electrolysis.

The newly formed sanitizer is then recirculated into the hot tub.


  • Provides bathers with water that’s gentle on both their bodies and swimwear
  • Compared to chlorine/bromine, using salt will cost less over the long term
  • Salt raises the buffering capacity of the water. This means your pH, total alkalinity, and calcium hardness levels will be better protected from fluctuations.


  • The amount of salt needed for these systems is substantial, and can result in corrosion issues with the tub, filtration system, and even the deck.
  • The conversion time from salt into chlorine/bromine can take up to 3 days, requiring traditional sanitizer when starting the tub, and shocking it.
  • Salt generators only last between 2 and 5 years. The power supply usually lasts longer, but you’ll have to replace the salt cell if you want to keep using this cleaning method.

6. Enzymes

Enzymes are essentially proteins, and work by breaking down the molecules of organic pollutants to a very small size. This helps the tub’s sanitizer to easily kill them.

Adding them to the water is as easy as pouring the correct dosage into your tub.


  • Is an all-natural spa supplement that makes the water feel gentle while reducing irritant issues for bathers
  • Spas are prone to oils building up in the water, resulting in foam issues. Enzymes break down these oils so foam doesn’t have a chance to form.
  • Enzymes have a lot of staying power in your tub. After they break down organic pollutants, they continue to work. Eventually they need replenishing, but they remain effective for long periods of time.


  • Enzymes can’t disinfect or kill harmful things in the water, which is why chlorine or bromine must be used with them
  • An incorrect dosage of enzymes can be detrimental to the tub. If there’s too high a level, it can result in an overly foamy spa.
  • While they’re easy to add to the water, enzymes are an extra chemical and extra cost to add to your budget.

What About Shocking Your Hot Tub?

Despite all the alternative routes you can take when it comes to sanitation, your hot tub will still require weekly shock treatment.

Aside from biguanide, these methods only reduce the consumption of harsher chemicals like chlorine and bromine.

You’ll still need to keep a low level of them in the water, and shocking will still be required to kill off harmful pollutants that these chemical alternatives can’t eradicate.

Where biguanide is concerned, it’s its own separate entity when it comes to water cleaning. The product line you use will have their own brand of shock which you’ll add to the tub. Otherwise, you’ll need to use non-chlorine/bromine shock.

Make The Switch!

Traditional sanitizers don’t have to be the be-all end-all when it comes to keeping your tub water clean. 

Any of the above hot tub chemical alternatives can provide you with more gentle water, while keeping your spa just as clean. The only remaining question is: which one will you choose?

Categories: Hot Tub Care, Hot Tub Chemistry