Non-Toxic Sanitizing

We are continually monitoring the evolving science of hot tub sanitizing to provide our customers with the most current information. Below is a list of sanitizers that we have found to be safe, effective, and practical for soaking tubs.

Although it’s up to each person to decide how they want to go about sanitizing their soaking tub, we strongly recommend using only non-toxic sanitizers that kill bacteria without harming people – for the simple reason that toxic chemicals such as chlorine and bromine run counter to the very purpose of a soaking tub – health and vitality.

Soaking Tubs are Different

With a soaking tub you can avoid the complicated hassle of dealing with toxic chemicals and water chemistry that is a necessary part of owning a conventional spa. Because soaking tubs have a lower water volume, they can be frequently drained, making sanitizing much easier and simpler. Many tub owners avoid sanitizing chores altogether by draining their tub after each use. When water is kept in a tub for more than one day; however, a sanitizer must be used to eliminate potentially harmful microorganisms. And yes, they work. You can effectively keep a soaking tub free of bacteria by using non-toxic sanitizers.

Become an Expert

Everyone who owns a soaking tub needs to educate themselves about sanitizing to keep their tub clean and safe. Here are the steps:

  1. Research the various options and weigh the pros and cons. (see below)
  2. Choose a sanitizer that makes sense to you.
  3. Develop a routine.
  4. Use test strips specific to your sanitizer to check the concentration in your tub.
  5. Finally, test your water with a bacteria test kit to find out how well it’s working and help you fine-tune how much sanitizer to use. (

By doing this, your tub will be pristine clean and put you in complete control.

What’s the Problem?

Bacteria introduced by tub users are the primary health concern. In a freshly filled tub; however, bacteria from users are diluted to such a low concentration that they are not a significant problem. Bacteria only pose a threat when they are allowed to multiply over time in warm water with organic matter from the skin. The optimum time to sanitize, therefore, is immediately after people get out of the tub. Only a small amount of sanitizer is required while people are using a tub.


1. Hydrogen Peroxide

We recommend hydrogen peroxide (H2O2) as a top choice for sanitizing a soaking tub. It’s a pure and natural liquid, composed of the most important life-giving substances – water (H2O) and oxygen (O2). It has a molecular structure made of water with an additonal extra oxygen atom attached (H2O + O1 = H2O2). Interestingly, hydrogen peroxide is beneficial to plants, so tub water can be safely drained onto lawns and gardens.

How Does it Work?

Since hydrogen peroxide is very unstable, it releases an oxygen atom when it comes into contact with microorganisms to form stable water (H2O). The oxygen atoms kill bacteria and viruses by attaching to and destroying their cell walls. (more)

(More) – Oxygen is abundant in our atmosphere in a stable paired form, O2. Our life depends on breathing O2. Unpaired oxygen, O1, however, is very unstable and seeks to find stability by attaching to another molecule or another O1 to form stable oxygen, O2. It is said to “oxidize” whatever it attaches to.

How Is it used?

The only type of hydrogen peroxide that should be used for sanitizing a soaking tub is “Food Grade”, usually available in 19% to 35% solutions. The recommended amount of 35% is ¼ cup or two ounce per 100 gallons of water. Because hydrogen peroxide continually breaks down in the tub, it must be added regularly. The most effective time being shortly after people get out of the tub. Hydrogen peroxide test strips indicate the concentration in tub water. 70 ppm minimum is optimal.


In storage, hydrogen peroxide naturally degrades into water and oxygen at the rate of 6% per year at 68° F in a closed container. The degradation rate doubles with each 18-degree rise in temperature, therefore, we recommend storing it in a refrigerator when outside rise temperatures above 75° F.

Note: The type of hydrogen peroxide used in spas as a shock treatment, contains a stabilizer that inhibits degradation and prolongs shelf-life; however, it should only be used if water is held for several days. When water is held longer and this type of peroxide is continually added, the tub water can become cloudy.

Where to Get It?

We recommend purchasing food grade hydrogen peroxide from internet sources to get the best price:

  • – 352-564-0404
  • – 352-563-5400
  • Canada: – 705-522-4089

Food grade hydrogen peroxide is often available from hydroponic supply stores.


This highly concentrated form is very caustic and can damage skin. Gloves and eye protection must always be worn when handling. It must be stored in a cool dark place or refrigerated.

2. Mineral Ions

Mineral ions – copper, silver, or a combination of both are another effective sanitizer. They are added to a soaking tub in a liquid form. Tub water properly treated is safe for people, since the copper level required in your tub is actually lower than the standard set by the EPA for drinking water. 

How Does It Work?

Mineral ions kill bacteria and algae by introducing reactive ions into the tub water. They disrupt the cell structure and chemical makeup of microorganisms, eliminating them in a safe way.

How Is It Used?

Ionic minerals are added to tub water at a specified concentration. Very low maintenance is required once the correct level is established. Copper test strips allow you to maintain the proper concentration level. (The concentration of silver ions cannot be tested.) A bacteria test kit will indicate if the mineral ions are working properly.

Note: Most manufacturers of ionic mineral sanitizers advise against using them in combination with hydrogen peroxide, as they can interact and nullify the effectiveness of both; however, ionic minerals can be used as a supplement to ozone.

Where to Get It?

Ionic Mineral Sanitizers can be purchased from online hot tub supply outlets.

Recommended Brands:

  • Cleanwater Blue
  • Instant Ions
  • Pristine Blue


Ionic minerals cannot be used with a galvanized stock tank, as the copper ions will react with the zinc coating of the tank and make it ineffective.

3. Ozone

What Is It?

Ozone (O3) is a very unstable and reactive gas composed of stable oxygen (O2), with an added oxygen atom (O1). Ozone gas is produced when oxygen (O2) is exposed to “corona-discharge” by an electrical device called an ozonator – adding an extra oxygen atom (O2 + O1 = O3).

How Does It Work?

Ozone sanitizes water using the same principal as hydrogen peroxide – by releasing unpaired oxygen atoms when they come into contact with micro-organisms. This volatile reaction destroys the cell walls of bacteria and viruses.

How Is It Used?

Ozone gas is injected into hot tub plumbing in the form of minute bubbles and circulated into a tub by a pump. Ozonators are typically used in combination with an electric heating system that has an electronic timer to automatically cycle on the ozonator and pump several times a day.

Since ozone is in the form of very small bubbles, it does not make good contact with surfaces due to “surface tension”, therefore, supplement it with a small amount of sanitizer such as hydrogen peroxide or ionic minerals for complete effectiveness.

Note: For ozone to have maximum effectiveness, it should be used in combination with a “flash reactor”, which fractures ozone bubbles into smaller bubbles and mixes them thoroughly in water. Only the Mazzei brand injector and flash reactor can produce top performance. Inexpensive ozonators do not use Mazzei components. (


Although ozone is a very effective method of sanitizing, it is not a practical choice for do-it-yourselfers unless you are retrofitting a spa because it requires external plumbing and a pump. For tubs with a non-electric heating system, we recommend either hydrogen peroxide or a mineral sanitizer as a more practical and cost-effective way to sanitize.

Note: Island Hot Tub provides the only stand-alone electric heating system on the market that includes an ozonator.

4. Enzymes

Although not a sanitizer, enzymes can increase the effectiveness of a sanitizer by eliminating the organic matter that bacteria feed on. Derived from plant extracts, enzymes work by breaking down the cell structure of organic matter so it can be easily filtered out. Note: Enzymes must be used with a system that has a pump and filter.