Chemical Free Hot Tubbing
Chemical Free Hot Tubs; is it possible?
This is a very popular subject and a question customer's ask us all the time. The answer is NO because in addition to keeping your tub sanitary you need to keep the water balanced (adjusted for alkalinity, pH and water hardness). The later involves adding products which adjust the water chemistry to bring it in line with ideal "pH Neutral" levels. Having neutral water to begin with is very important as it affects how the water reacts with the heater elements, your skin, and how effective the sanitizers will be. Without neutral water, problems will quickly arise. Balancing chemicals such as pH up, pH down, Alkalinity rise, calcium increase, are seldom discussed as chemicals however these by definition are certainly chemicals, and as such make it impossible to say that NO chemicals can be used.
When most people ask about "chemical free systems", they are usually referring to traditional sanitization chemicals such as Bromine and Chlorine. "Can I use a wooden hot tub without any harsh sanitizing chemicals such as chlorine and bromine?" As suggested, for the sake of this article we will consider "chemicals" to be considered the Halogens family in the form of Bromine or Chlorine. So the question should be reframed to, "are there effective skin and health friendly alternatives to using chlorine or bromine in keeping a hot tub sanitized?"
It seems very logical that customers seeking a natural hot tub soak provided by a wooden hot tub, would also want that experience to be free of these chemicals. The problem with any type of hot tub, wooden or plastic, is that the high temperature conditions, ratio of persons per unit volume of water, and frequent use, are a perfect mix for breeding bacteria and algae. 3 persons in a small hot tub is equivalent to 300 people in a backyard pool.
In order to answer the question of safe alternatives, we 1st must understand what function chlorine and bromine have in a pool or hot tub. Once we clearly understand their functions we can then address substitute products.
The USA's EPA certifies Chlorine and Bromine as two safe chemicals for water control in pools and spas. Specifically they certify their ability to safely sanitize and oxidize a pool or spa. When used properly these chemicals are considered safe, otherwise they would not have EPA and other countries equivalent approval. Until recent times, these chemicals have long been considered the main pool and spa sanitizers.
The debate on which chemical to use (bromine or chlorine) is ongoing, however on a wooden hot tub the choice is one sided. Bromine is the sanitizer of choice simply because Chlorine under specific circumstances can actually break down the wood fiber causing irreversible damage to the tub. Besides this important fact, Bromine is considered to have fewer odors and is more stable than chlorine at high temperatures (chlorine "gases off" after 98 degrees).
Now in order to discuss alternatives, we need to clearly understand the two processes that bromine (chlorine) provides in a hot tub or spa. These are to sanitize and to oxidize, as this is ultimately the functions we require when looking for alternatives..
What is a sanitizer? A restricted definition for a "sanitizer", as used in the pool and spa industry, is any product that destroys live bacteria and viruses, present in the water or on wetted surfaces. Chlorine and Bromine's are EPA approved sanitizers in that sense. Under the right concentration and provided the pH is in the 6.8-7.5 range, which is comfortable for our skin, both will kill any bacteria that impose a heath risk. They are members of the Halogen family and when combined with water form a sanitizing chemical HOCl (hypochlorous acid) or HOBr (hypobromous acid) which when in contact with bacteria and viruses will destroy them (depending on the contact time and concentration of the chemical). Bromine and Chlorine when dissolved in water further also produce oxidizer radicals, which will be discussed later. We will limit our choice to bromine as chlorine can actually attack the wood and break down the fibers. It should be obvious however, that bacteria and virus killing properties are not unique to only chlorine and bromine. The question will be whether the alternatives can get the job done effectively or entirely on their own.
What is an Oxidizer?
When bromine gas is dissolved in water it forms the sanitizer HOBr and the oxidizer OBr- (hypobromite ion). At the normal target pH levels of 6.8 -7.5, a very high percentage of the bromine is converted to HOBr and thus it is effective in its sanitizing role, but the OBr- ions have a relatively low concentration and therefore bromine is not so effective in its oxidizer role. Thus in a bromine system we recommend using an additional oxidizer (MPS or Ozone) to aid in oxidizing contaminants such as oils, lotions dead skin as well as destroy bacteria quickly.
What has all this got to do with alternatives to chlorine and bromine? We need to understand how these products work to lay a framework for understanding the alternatives.
What is Ozone?
Ozone is produced by either passing an electricity discharge through air or shining uV light through air. With either method a certain percentage of the stable form of oxygen, O2, that comes in contact with the electric discharge or uV light is transformed, to the less stable O3 molecule (ozone). The ozone, however, is looking to rob electrons so it can get back to a more stable form. That is what makes it an excellent oxidizer. The ozone enriched air is injected into the hot tub water where it can then oxidize bacteria and contaminants. Ozonators for consumer hot tubs come mostly of the uV type. Corona discharge ozonators produce considerably more ozone but are intolerant to high humidity and to keep them working and not have them fail prematurely the air needs to be dried. To do this all properly, results in complete corona discharge ozonators being quite expensive, relative to uV systems.
Does ozone have draw backs? Ozone dissipates very quickly and there is no such thing as an ozone reserve, thus if no ozone is being injected, such as if the filtration cycle is off, there is no oxidation or sanitation going on. For the consumer there is also no practical measurement for ozone. And as mentioned ozone does not destroy all bacteria and some use of bromine and of a non-chlorine shock still needs to be used.
What are Mineral Ionization Systems?
What are Natural Enzyme Products?
MPS - none chlorine shock
So. for those who are disposed against bromine or chlorine, there are workable alternatives. The above mentioned alternatives are the ones we have found effective in conjunction with a wooden hot tub. We will not sell products that can lead to early wood deterioration, which means we avoid selling certain products and caution customer to check with us before using any off-the-shelf chemicals. Most Pool and Spa sales people know very little about wooden hot tubs! Even if you own another brand of wooden hot tub, or own a plastic spa, you can still use the same chemical alternatives that we use. These are available at Cedar Tubs Direct http://direct.cedartubs.com/ . This store contains all the products we recommend. You can also sign up to receive our quarterly Tub Talk news letter!
Dan Jung -President
Feb 23, 2017
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