Some of the most common questions you’ll get as a float center operator involve the cleanliness of your tanks. We’ve covered the basics of testing and maintaining your saltwater elsewhere, but we wanted to delve more into the various methods of sanitizing your float water.
One thing to know right off the bat is that at least some method of active sanitation is necessary to run a clean float tank. While there’s a huge amount of Epsom salt in the water, and that salt does have a beneficial effect in helping keep the float water clean, it’s generally agreed upon that the salt itself is not enough to keep your floaters safe. This initial study by the Float Fund shows some details about the impact that the Epsom salt has (and doesn’t have) on certain bacteria.
Below is an introduction to some of the most commonplace sanitation methods used in float tanks. These are generally either chemicals that go in the water or devices that attach to your filtration system. We’ll be discussing chlorine, bromine, ozone, UV, and hydrogen peroxide, which account for the sanitation methods used on nearly every float tank on the market.
Many float tanks use a few of these methods in conjunction with each other, but if you decide to combine methods, be sure to understand the various chemicals you’ll be combining. Certain sanitation methods work well together, but others will work at odds with each other, lowering the effectiveness of both.
A word about words
One thing you’ll learn very quickly as you start talking to your health department official is that they have a whole health department language they speak. Some of their crazy health department words may even sound like words you’re familiar with, but for health regulators certain words have very specific meanings that us laypeople aren’t quite used to. One of these is the word “disinfection.”
For health regulators, disinfection specifically means killing off 99.9% of some microorganisms, which is often the benchmark they use for safety.
For a chemical to be considered a disinfectant in a pool, it’s also required to be registered as a disinfectant by the EPA. Basically, it’s not a word you want to throw out haphazardly. More generic words are “cleaning,” “water treatment,” or “sanitizer.” The word “sterilization” is actually even more intense than disinfection and is usually the level of cleaning required for surgical equipment.
Chlorine or Bromine
Chlorine and bromine are definitely the big boys in the pool and spa world. In fact, here in the US and Canada you’d be hard pressed to find a commercial pool or spa that isn’t required to use chlorine or bromine. They both are in the “halogen” family of elements, existing in the same column of the periodic table, and as such are both highly reactive with other elements and molecules. It’s through these reactions that they end up combining with various bacteria and germs in the water, killing them in the process.
For our intents and purposes here, we’ll be talking about chlorine and bromine interchangeably. The only difference worth noting is that bromine is typically used only in warm water (like in hot tubs) because it tends to let off less of a smell in warmer water than chlorine does.
One important thing to know about chlorine/bromine is that they are floating around throughout the whole body of water, ready to kill the microorganisms they encounter. In health department lingo, the fact that some sanitizer is present throughout the water means it has a “residual.” This is as opposed to something like UV, where the the UV rays are only hitting the water that directly passes in front of the UV bulb in the filtration system.
This residual can be important for two reasons: in a body of water where multiple people are swimming next to each other, you’d want something in the water to kill any harmful microorganisms from one person before it reaches the next person and gets them sick. A residual also provides an easy thing to measure, meaning health inspectors can come in, take a scoop of water, and test it to make sure the levels are right.
Chlorine and bromine have been used to disinfect pools for longer than any of us have been alive. For the most part, they’re pretty good at killing harmful microorganisms (with some exceptions), and they’re good at doing it quickly. One issue with chlorine/bromine is that as they react and combine with the various organisms they’re killing, weird stuff gets created, some of which can be harmful to our health. The health department calls these potentially harmful results of the chemical reactions “disinfectant by products” or DBP’s Many of the health risks people associate with chlorine/bromine are actually from these DBP’s, not from the chlorine/bromine itself.
How much of a concern DBP’s are to our health is a topic that’s up for debate in the pool/spa world. In outdoor pools or well-ventilated indoor pools, the amount of airflow may blow away any DBP gases before they really harm anyone. However, float tanks tend to be small, enclosed, minimally ventilated environments, raising the concern over the potential exposure to DBP’s in the air. The other consideration is that there may be less DBP’s present in float tanks than in typical pools and spas. DBP’s are only created when chlorine or bromine react to something in the water, and because everyone showers before they enter the float tank, the amount of stuff they’re bringing into the water that chlorine/bromine would react to could be much lower than a pool or spa.
As far as we know, no one has actually tested the air inside of a chlorinated/brominated float tank to measure the levels of various DBP’s, but the theoretical health risk is enough to make many people in the industry averse to using chlorine or bromine in a float environment.
While chlorine and bromine are generally considered effective disinfectants, and have been well researched and are well understood by the public health community, there are some practical downsides for using them in float tanks.
One very practical concern is that even with a well run system, it can be difficult to completely avoid the smell produced by chlorine and bromine. This is obviously at odds with the never ending goal at our float centers to reduce as much sensory stimulation as possible.
Another practical concern comes from maintaining proper chemical levels. As far as we know, there is no chlorine or bromine test kit out there that measures the levels accurately in our salty float water. Chlorine and bromine also rely on proper pH and alkalinity levels for them to be effective, and we’re also unaware of any pH or alkalinity testers that are accurate with float water. (If you think you’ve found an accurate test kit for any of these, please let us know! firstname.lastname@example.org)
At the end of the day, the choice of which sanitizer to use may not be entirely up to you. There are some health departments that require float centers to use chlorine or bromine, and some health departments that specifically ban float centers from using them. As the body of research around float tank sanitation grows, we’ll have some more clear answers to help inform these decisions.
Another option you see on some float tanks is ozone. Ozone is a gas (O3) that is created by a device attached to your filtration system called an ozonator. The ozonator injects the ozone gas into one of the pipes in your filtration system while the pump is running, typically though a piece called an “injection manifold.”
Ozone is a powerful sanitizer, typically regarded as more powerful than chlorine and bromine. It’s sometimes used in pools and spas because of its ability to kill some things that chlorine/bromine can’t, and because of its ability to help breakdown some of those disinfectant by-products that get created during chlorination/bromination. Commercial pools and spas can’t rely on using just ozone by itself, because unlike chlorine and bromine, ozone doesn’t have a residual. While it does last in the water, it is short lived. How long it lasts is based on many factors (such as temperature of the water), and you’ll hear different information out there, with numbers ranging anywhere from 30 seconds to 15 minutes. Regardless, even at the high end, it doesn’t last long enough to be continuously floating around the water in pools and spas the way chlorine or bromine would.
In float tanks, it can also be difficult to measure. Pools and spas typically rely on something called ORP sensors (oxygen reduction potential) to gauge the effectiveness of ozone, but, as with other testing equipment, ORP sensors seem to have issues with the high salt content of float solution.
The other concern with ozone again comes back to air quality. Too much ozone gas can be harmful to breathe in, and even small amounts can have negative affects when breathed in regularly (which is a risk for you and your employees). There are ways to properly mitigate this risk, and it’s something you should ask your manufacturer about if you are purchasing a tank with an ozone system.
Ozone can be used in conjunction with chlorine or bromine, and it can also be used with UV. There is a nice effect that happens when UV hits ozone gas, which is that something called Hydroxyl Radicals are formed. These are extremely short lived particles (less than a second) that are very effective at killing microorganisms, more effective than ozone or UV would be on their own.
UV stands for Ultraviolet light, a wavelength of light that is higher in frequency than the visible light spectrum. Like ozone, UV is typically only used in addition to chlorine and bromine in commercial pools and spas, not by itself. This is mostly because UV does not have a residual. The UV bulb sits inside of a tube that is part of the filtration system, so the only time the microorganisms are exposed to the UV light is when they pass through that system. While UV is good at killing a number of microorganisms (including some that chlorine/bromine have trouble with, notably cryptosporidium), the fact that it can only affect the water that passes directly by it leads to many people using UV in conjunction with another system of sanitation.
The good news is that UV seems to work well with all these other sanitizers we’re talking about. In addition to packing its own sanitation punch, with chlorine and bromine UV can help break down those disinfectant by products. With ozone, as mentioned before, it creates those hydroxyl radicals. It also creates those hydroxyl radicals when used in conjunction with hydrogen peroxide, so other than added cost of the UV unit, there is typically no downside for having UV on your system.
One difficulty with UV again comes from how to measure it. Commercial pools and spas typically have sensors in their UV units that can detect the level of UV output the bulb is producing, but UV systems like that can be quite expensive, so you don’t see them on many float tanks. Without a sensor like that (or an accurate ORP sensor), there is nothing you can look at on a daily basis to make sure you’re getting the UV output you’re suppose to. The UV bulb does emit visible light as well, but just seeing the light turn on does not necessarily mean the UV range of light is actually being produced. This means you’re left relying on the system working the way the UV and float tank manufacturers say it will without ongoing verification that everything is operating as it should be, which some health departments don’t look favorably on.
Hydrogen Peroxide (H2O2)
The last thing we’ll be talking about is Hydrogen Peroxide, or H2O2. Hydrogen peroxide is the weakest of the sanitizers on this list, and is generally considered to not be powerful enough to be solely relied on in pools, spas, or float tanks. In fact, it’s typically considered mainly as an oxidizer, meaning it helps break down the bits of microorganisms that are left after they have been inactivated.
When H2O2 is used, it’s used in conjunction with UV, and in this scenario you want to consider UV as the main force of sanitation, and peroxide as the helpful force alongside it. Many people hit roadblocks with health departments because they describe their float tanks as being cleaned primarily by hydrogen peroxide, which can put some warning flags up for regulators.
In addition to being an oxidizer, H2O2 does create those hydroxyl radicals when combined with UV, and other than chlorine or bromine, it is the only other thing on this list that has a residual. One of the biggest benefits of hydrogen peroxide is that it simply breaks down into water and oxygen, and doesn’t result in any DBPs or other air quality concerns. As a result, a UV/peroxide system has the lowest chance of of having “side effects” that create inadvertent health risks for your customers and your staff. The downside is that of the sanitation methods we’re discussing here, a UV/peroxide system has the least amount of available data and documentation to show its cleaning efficacy. This can be a very big roadblock when working with health departments, and is often the main reason why regulators will not allow float centers to use only UV and hydrogen peroxide.
One piece of good news is that unlike almost everything else we’ve discussed, it is easy to accurately measure hydrogen peroxide. In fact, there is one test kit from Taylor Technologies that has been tested and confirmed by them to work accurately in float tank water. Hopefully this is a sign that other float-tank-specific testing products will come out soon.
Depending on where you’re attempting to open, you may hear about a need for NSF certified components, or even an NSF certified float tank. NSF International is a private company which certifies products to ensure that they meet a set of safety guidelines which they create (called Standards).
Becoming NSF certified is something that a float tank manufacturer can choose to do, not something you need to do at your float center. As someone purchasing float tanks, it’s up to you whether you want to purchase a tank that is NSF certified, or that uses NSF certified components.
There is a lot of debate within the industry as to whether float tanks being NSF certified is good for the float industry or not. Some say that NSF certification can help ensure safety and help get through some of the more difficult health departments to deal with. Others say that the extra cost and limitations of the certification will stifle growth and innovation, and would prefer to work directly with government health departments for safety regulations rather than through an independent company.
At the time of this writing, there are no health departments out there which actually require an NSF certified float tank, and the future of wide-spread adoption is unknown. The best option at this point is to be sure to at least meet whatever your health department requires, and if you choose to go above and beyond that it certainly won’t hurt. Even in the case of a health department adopting a requirement for an NSF certification, it’s not unusual to see existing businesses grandfathered in, or given a reasonable amount of time to meet the new requirements.
It’s important to note that while this is a general overview of these sanitation methods, the complexity and nuance of all of this goes much much deeper. There are still a lot of unknowns in the world of float tank sanitation. It can also be hard to discuss components of sanitation and their effectiveness individually, because at the end of the day your pump, your filter, the design of your tank, the quality and size of these components, and your diligence in operations and upkeep all come together to keep your float tanks clean and safe for your customers.
If you’d like to go one level deeper and learn more about float tank sanitation and equipment, we recommend watching the free water treatment section of our online apprenticeship.