Hot Tubs and Spas purging and cleaning Tub maintenance

Spa Marvel review – the enzymes

Greetings Hot tub enthusiasts.  This post is about a class of products that have appeared in the Spa industry known as “enzymes”, and more specifically the product, “Spa Marvel”.  Readers of this site may have already seen my review of the enzyme-based purge product from Natural Chemistry, but until now I have not evaluated an enzyme-based maintenance product — so this would be interesting.  As you will see below, Spa marvel makes some very interesting claims which I will evaluate.

Background and approach

The use of enzymes as a spa maintenance product presents a different vector to my normal  hot tub regimen — my regimen is a simple, “as few chemicals as possible” use of chlorine and/or bromine-based protocol with frequent drains and biofilm purges as described on this site (please see the above link, and “Hot Tub Home” in the left nav).  Spa Marve’s claims for an enzyme-based maintenance product intrigued me, not only for what they claim, but also for what they do not claim and cannot prove.

I am referring to the ~$60 “Spa Marvel Water Treatment & Conditioner 16 fl oz”, product, which I purchased from Amazon and used according to the label directions.  For sake of completeness, I’ll point out that to give this product every possible advantage I first purged my spa with “ahh-some” (a product that “wipes the floor”, if you will, against an other purge product I have tested) and started with fresh, clean water.   As you will see below — I didn’t even use my spa for the first few weeks, just so I could study the products performance under controlled conditions.  I followed this with real-world use tests and several bather-hours in Marvel-dosed water.

Minimalist spa maintenance

In the paragraphs below you will find several references to a “minimalist” approach to spa maintenance.  Essentially, this is a protocol that solves nearly every spa maintenance problem on the planet, and renders solutions such as “Spa Marvel”  unnecessary.   I’ve been using such a protocol great success, along with many other spa owners.  Here’s my protocol in a nutshell and what I mean by “minimalist”:

  • To start with a clean spa I purge with a product known as “ahh-some” on every drain.  This rids my spa of, well, everything.  Please see the introductory materials (“Hot Tub Home”, in the left nav)  to read more about my journey with biofilms and how I use ahh-some.
  • I fill my spa with tap water from an outdoor spigot, and balance my water with easy-to-obtain products like pH reducer.  At this stage, I care very little about Total Alkalinity (TA) unless it is way off.  High TA levels are problematic for most spas.
  • Shock with chlorine.  This is an important first step.  you want to make sure and kill all the bad guys the might have started growing
  • heat and use the spa!  the only chemicals I use on a regular basis are chlorine and pH reducer.  I do NOT chase TA as a parameter — in a portable acrylic spa,  this does not have to be as high as the spa stores tell you.  I let TA fall to about 50ppm, which helps greatly with pH control.   Note: this is unique to the portable, acrylic spas — you do NOT have to achieve certain numbers or target a “zero saturation index”.  In fact, for those who care about details and understand the “Saturation Index” parameter itself, I’ll simply say that its ok to let this go negative (but only for portable acrylic spas).
  • I use dichlor (chlorine granules) for the first few days until I have introduced a grand total of approximately 30ppm of chlorine (over time).  After that I use pure, unadulterated, ordinary, plain, regular Clorox bleach for my chlorine source.  This makes a spa store heads explode but what they don’t tell you is that this is profoundly effective, safe, and cheap.  No, it does not destroy vessel walls, lids, filters, heaters, covers, or anything else, but it does cut into their dichlor sales!  You just have to be careful not to splash it on your tub walls — dump it into the middle of your spa (not the filter compartment) with the jets running full bore. I’ve been using bleach for at least 10 years now, and never once damaged anything.  Don’t believe the scare tactics!
  • I let pH drift up to 7.8 per CDC guidelines.  If it touches 8.0 its time to reduce pH with dry acid in order to maintain chlorine effectiveness.  This is an important point which I mention later, in the context of certain recommendations to run higher pH values.
  • I am experimenting with a maintenance product claiming to kill/control biofilms.  If I’m going to use a maintenance product its going to be one that actually kills bad guys, not one that just competes for their food supply.

Spa Marvel Initial Impressions

I’ll comment on each of the manufacturer’s claims later in this article but for now I’ll offer my impressions after using my spa with Marvel-dosed water:  Quite frankly, the only thing I noticed was a bit more foam.  Beyond that, I did not notice any “softness” improvement, nor was my water easier to balance.  I remind the reader that my spa maintenance regimen is already “minimalist” , and very effective — so  my “squeaky clean” spa wasn’t broken and it didn’t need fixing.  For me, the product is an expensive placebo — a solution in search of a problem, if you will.  My overall conclusion is that there are better and less expensive ways to address the issues that Spa Marvel purports to solve.

As you read on, please keep in mind that my evaluation of Spa Marvel was performed in comparison to this already proven-successful, minimalist regimen.   However,  if  Spa Marvel’s claims turned out to be a better protocol, I would definitely take notice:  Who, after all, wouldn’t want to reduce their use of chlorine or leave the spa un-attended for days at a time?  So I was on the edge of my seat, as it were, to investigate  these claims further.

Enzymes and bad guys

First of all, I should point out that enzymes are real — they aren’t just a fiction. As I have already pointed out (in the above link), Enzymes do something, so the fact that people use Spa Marvel doesn’t surprise me.  What surprises me is the number of extraordinary claims the product makes, and how  carefully they are worded.   The “Man behind the curtain” is really only two things: (1) the enzymes that compete for bad guys’ food supply, and (2) a surfactant that makes the water a little “wetter”.

It’s important to understand  that the Enzymes in Spa Marvel have no power over the bad guys  themselves that could be present in the water.  They only have power over their food supply.

Recognizing the above, the operating principle of Spa Marvel is actually sound, even if risky: Compete for the bad guys’ food supply and they won’t form or grow.   Unfortunately, in actual practice this is dangerous, in my opinion;  In my experiments Spa Marvel didn’t produce any benefit for me, which I will describe in more detail below.

The disclaimer

The opinions expressed here are mine and based on my experimental results and my research.  They are not intended to infer wrong-doing on the part of Spa Marvel, even though I call out some of their claims and choices of words, which I find misleading.  The U.S. is a free country, and manufacturer’s are free to make claims and to promote their products and, at the same time, reviewers like myself are free to opine about them as well.  That’s what I’m doing here.

As with all of my product reviews, all it takes is new or updated information for me to change an opinion and I offer that here as well.  If I say something that is incorrect I will make a correction as soon as I am aware of the need to do so.

Magic and Tradition

I mentioned earlier that each of the Spa Marvel claims is very carefully worded.  They are so carefully worded, in fact, that one has to really pay close attention to learn what they are really trying to say.   I try to be as objective as possible in all of my experiments,  and I have attempted to be as objective as possible here as well — but I quickly learned how  difficult  it is to say something objective about a product that is deliberately subjective!  My personal opinion is that Spa Marvel is selling more emotion than science.

The first thing we need to do is define the expression, “traditional spa water care” because  Spa Marvel claims to be better than that.  I can’t comment on the nature of spa water care that Spa Marvel considers “traditional”, but given the set of Spa Marvel claims it must be something pretty abysmal.  I acknowledge that some spa stores prescribe unnecessary chemicals and that this practice, combined with improper use of those chemicals can produce some bad results, and even chemical rashes in some cases.  So, I can think of some bad-maintenance scenarios in which one could introduce Spa Marvel and see an improvement — but I would also point out that putting lipstick on a pig still results in a colored pig, and that it’s better to eliminate the problems in the first place rather than covering them up.  I’ll put it this way:  If the Enzymes in Spa Marvel really make the dramatic improvements that are outlined in their claims, then you are already making some very bad mistakes in your spa maintenance regimen.

So, just as a reminder:  I have evaluated the Spa Marvel claims against a well-maintained spa “minimalist” spa regimen (described above), not a poorly maintained spa or one that is in trouble.   I find that I am using fewer chemicals in my spa without the use of Spa Marvel than with Spa Marvel–simply by eliminating the use of Spa Marvel!

The Claims

With one possible exception,  I find that all of the Spa Marvel claims for certain water care victory are based on the “Straw-man” Argument.  This technique builds up a set of horrible conditions and then comes to the rescue.  I say this  because Spa Marvel didn’t benefit me — I had none of the problems they purport to solve!  The one possible exception to this is the potential benefit of reducing the load on your filters, which I explain further, below.

Without further ado, here are the claims and my comments on each one,  based on experimental results.

  • “can reduce and eliminate the need for many of the chemicals used in traditional spa water care” .  Use of the word, “can” signals to me that there is no particular product performance claim, nor is there any objective criteria against which one can evaluate the product. There is no list of traditional chemicals that one can throw away, for example.   In my spa,  I found that the use of Spa Marvel did not eliminate nor did it reduce the need for any of the chemicals I personally use.

Claim status:  plausible, but only if you already have a problem and you are using unnecessary chemicals. The best solution here is not Spa Marvel itself, but a change to your maintenance protocol.  

  • “Traditional spa treatment causes itching, rashes, odors or coughing”.   The key here is how to define what “traditional spa treatment” is.  I, like a great many others,  have been maintaining hot tubs with traditional chlorine and bromine treatments for decades,  and never once encountered itching, rashes, odors or coughing.  The important point here is that if you experience any of these things, it means you are not maintaining you spa correctly in the first place.  I’m calling foul on this one because it is another “straw-man” caricature .

Claim status:  busted.  No, traditional spa treatments do not cause these things.  The improper application of traditional spa treatments  can certainly cause these things, however.  A great many spa owners successfully use traditional chemicals such as chlorine and pH control without any of these problems.

  • “it will take a LOT less chlorine to maintain desired levels with Spa Marvel in your spa than without”.  This is another slippery claim that is technically true but doesn’t mean anything useful.  However, I decided to test this claim on its on merits.  I performed a controlled experiment in an outdoor location where my spa is subject to dust and such — simulating the “Absentee owner” scenario with no bather load.   In my experiment, I maintained chlorine levels of approximately 2-5ppm for two successive two-week test periods– the first without Spa Marvel and then another two weeks after dosing with Spa Marvel.  Over each of the two-week tests I introduced the equivalent of about 13ppm chlorine (via dichlor) into my spa.  For the 2nd week (dosed with Marvel) I used about 20% less granular dichlor to achieve the same average chlorine level in my water. Note that any statistician will point out that my experiment is not statistically significant:   My result could be due to normal variability!  However, I’m going to give Spa Marvel the benefit of the doubt here because if the enzymes DO compete for the bad  guys’ food supply then (technically) this could reduce the amount of work that chlorine would have to do.  So Spa Marvel isn’t lying here;  they are just obfuscating the real truth and and making a big deal out of a nothing-burger.

Claim status:  probably true,  but its a moot point and truly a “don’t care” with no real practical benefit.  Let me explain further:

Note that  “less chlorine to maintain desired levels” is NOT the same thing as “lower chlorine levels!” You still must maintain chlorine levels of at least 3ppm  in order to kill the bad guys!  That means do not go below 3ppm.  let me repeat:  Do not go below 3 ppm Free Chlorine, no matter how many anecdotal stories you hear about people doing so without getting sick.    Please see my introductory materials in the “Hot Tub Home” section of this site (left nav) where I cite a study showing that biofilms (these are bad guys) can re-generate in 1-3ppm chlorine.  Current best practices call for chlorine levels of 3-5ppm.  The CDC’s website currently (at the time of this writing) calls for chlorine levels of 3-10ppm — which I find to be high (I have personally experimented with 10ppm chlorine and find that my skin is pretty unhappy at that level).   All of that aside, however,  with Spa Marvel in the water it may be true that you could use a smaller spoon when dipping in to the dichlor bottle, but you will still have to dip that spoon into the bottle just as often.  I’ll say it again:  Spa Marvel does NOT (officially) allow or promote lower ppm levels of chlorine in the water.

The marketing thrust (and anecdotal stories) of Spa Marvel gives the very distinct impression that one can actually lower the chlorine level in the water and still be safe.  But Spa Marvel knows that this is not true, as they have buried the following, very carefully worded, statement at the bottom of their home page (at the time of this writing):

“…respect your local regulatory agency’s guidelines and use sanitizers as required.”

Translation:   Spa Marvel does not change required concentration (ppm level) of chlorine  in your water

Now, then — isn’t it a good thing to “use less chlorine”?   That has a certain attractive ring to it:  “I’m going to dump fewer dichlor granules into my water…”.  I can even hear people all of the world rejoicing over the thought of going to the store less often to buy chlorine.   But is that really the objective — to spend less money on chlorine?  Your water still has to be kept at 3-5 ppm, and the only benefit that Spa Marvel brings to the table is that it will take fewer dichlor granules to achieve it.  But, if your objective is to save money, you can take that $60 you spent on Spa Marvel and buy a lot of chlorine.

I can already hear the marketing department trying to slap back:  “but if you dump fewer dichlor granules into your water, that is easier on equipment!” No it is not.  The stress on equipment comes from high levels of chlorine, not the number of granules used to achieve those levels — so if you are using chlorine properly in the first place,  dumping a bottle of Spa Marvel into your water isn’t going to make your pumps last longer.  Remember, Spa Marvel does not change the Chlorine requirements in your spa. You cannot get by with less chlorine in your water just because you poured a bottle of Spa Marvel in there, and the reason is simple:  Spa Marvel does not kill bad guys.  If one of your bathers were to step bare-footed onto the ground where they could pick up Pseudomonas bacteria, for example, that bacteria would continue to live in your water until it was killed with chlorine.  Please see the next bullet for more information on this bad guy.

  • “Eliminates hot tub rash”:  The term, “Hot Tub Rash” (upper case) is a well-known medical condition caused by the Pseudomonas aeruginosa bacteria (mentioned above)  which  “commonly inhabits soil, water, and vegetation. It is found in the skin of some healthy persons“.    Unfortunately,  Spa Marvel has used a broader definition of hot tub rash (actually mis-information if you ask me) to include the improper use of chemicals.  That way, they can conflate the two conditions (one caused by improper use of chemicals, and the real one caused by a Pseudomonas aeruginosa), so that  Spa Marvel can come to the rescue for both.  But we must be crystal clear:    By itself, Spa Marvel will not, in any way, kill the bacteria responsible for Hot Tub Rash as defined by the CDC, and they know it.  In fact, at the time of this writing there is a good article on the Spa Marvel site discussing (the real) Hot Tub Rash where they do acknowledge that this bacterial infection can only be killed with a sanitizer.   Yet,  the very first in the list of benefits listed on the Spa Marvel home page (at the time of this writing) is “Eliminates hot tub rash”, conveniently in lower case.  I’m calling foul on this one, due to obfuscating the truth with the mis-information that Spa Marvel eliminates hot tub rash.

Claim Status:   Busted and dangerously misleading.  True Hot Tub Rash is caused by a bacteria commonly found in the environment, thrives in warm water, and transmitted via aerosolization.  It can only be killed by a sanitizer such as chlorine — NOT by Spa Marvel.  Skin rashes caused by the improper use of chemicals are eliminated by proper maintenance protocols.  Spa Marvel may help, but it is not the right answer to either of these problems and, by itself, does not eliminate either of them.  

  • Reduces and eliminates cases of itching, rashes, odours  [sic] and coughing that can be associated with spa use.” :  This can only be true if the spa is already in trouble and not maintained properly in the first place.   Note the slippery use of the word “can be associated”, which signals the same (lack of) definition that we found in the word, “Traditional” used previously.  It basically means putting lipstick on a pig again, because if your spa has these problems for real (and not just some subjective association with them), there are very easy ways to fix them.

 Claim Status:  Busted, because Spa Marvel doesn’t address these things directly.  Proper maintenance protocols does address these things directly.  If your Spa has these problems, Spa Marvel isn’t the best answer – the best answer is to purge with a product called “ahh-some” and then follow a minimalist chemical regimen.  Put it this way:  if your spa promotes  itching, rashes, odours and coughing then you need to fix these things without Spa Marvel.  Spa Marvel may help,  but the root cause of these issues is not the lack of Spa Marvel in the water.  

  • Helps to prevent foaming and scum lines”:    Like me, a great many spa owners control foam and scum lines without enzymes and surfactants.  Given the way Spa Marvel works this claim is could be true, but here is the slippery language again:  “Helps” to prevent foaming and scum lines.    It probably does help if you are already experiencing a problem, but by how much no one will be able to say.  If my spa had scum lines I wouldn’t treat it with Spa Marvel I would clean my filters!   There is a small amount of TSP (a degreaser and surfactant)  in Spa Marvel so its plausible that this could keep scum in suspension more effectively than without the product in your water.  The other point I would make here is that the enzymes in Spa Marvel probably reduces the load on your filters, so if you aren’t taking care of your filters properly you could benefit.  Accordingly, I can think of a few scenarios in which a badly maintained spa with a scum line problem would benefit from Spa Marvel.

Claim Status:  Plausible, but only if you are not maintaining your spa very well and have a scum line problem 

  • “Minimizes scale build up from occurring in the spa’s plumbing”:     I wasn’t able to test this because I don’t have a calcium scale problem and I wasn’t willing to push my water out of balance to observe the product’s effectiveness.  Properly balanced water will not form scale deposits, but if your water is not balanced, then yes the TSP that is present in Spa Marvel could  provide some small amount of insurance against scale.  However, I would point out that if scale is a problem in your spa, this is not the answer:  There are much more effective ways to deal with it.

Claim Status:  Probably true, but this is a solution in search of a problem:  properly balanced water does not scale, and there are much better scale inhibitors on the market if you need help in this area.  

  • Improves filter efficiency”:  This is just confusing techno-babble.  Filter Efficiency is a well-known expression with a very precise definition that refers to the percentage of material blocked by the filter vs what is passed by the filter.  However, Spa Marvel has chosen to use lower case here which avoids this precision.  Technically speaking, a filter’s Efficiency is defined by its media, not by the condition of the water passing through it, so I call foul on this one.  Spa Marvel enzymes probably do reduce the amount of material that the filter media has to block — so that is a benefit if there is already a problem in that area.  I would only point out that normal preventative care for both the water and filters takes care of this problem.  If the claim was “helps make filter maintenance easier” I would mark the claim as “true”, but since they are claiming that Spa Marvel actually changes the performance of filter media (Filter Efficiency) I have to give this one a raspberry.   Perhaps Spa Marvel will take note of this blog and change their claim;  then I’ll change my tune as well, in a heartbeat.

Claim Status:  busted.  Filter efficiency is determined by the filter media, not the water passing through it.  Spa Marvel’s unfortunate choice of words here makes it difficult for me to support this claim, but as mentioned above, the product would tend to reduce the load on the filter itself.  Whether that is a problem or not that needs to be solved is a different question!

  • Enhances chemical treatment. You will use considerably less sanitizer to maintain levels than you would without Spa Marvel, which allows for less chemical wear and tear on lids, jets and equipment and results in increased spa longevity”:   I’ve already commented on the “considerably less sanitizer” claim,  but I’m having a hard time agreeing with “less chemical wear…”.  High levels of chlorine are hard on equipment for sure, but its the chlorine ppm level itself that introduces this stress.  Spa Marvel itself does not allow lower levels of chlorine in the water, and neither is the equipment longevity enhanced by pouring this product into your water.  If  you are using unnecessary chemicals, the answer is to stop doing that, not to add something else to your water.

Claim Status:  Busted.  Its the chlorine ppm  level in your water that causes stress, and the presence of Spa Marvel doesn’t change that one iota  

  • Supports optimal water balance. The ongoing need to adjust pH and alkalinity is greatly decreased when using Spa Marvel for your spa water treatment.   Cheerleaders support their teams too, but that doesn’t put cheerleaders on the playing field or make the team win.  “Supports” is the slippery word here, as there is no objective way to define what this means.   I had to reach out to Spa Marvel themselves to learn what is going on here, and to the best of my knowledge it appears that this claim is based on allowing a higher pH value — not any inherent ability of Spa Marvel itself to control rising pH (one of the most common challenges in a Chlorine spa).   When talking to Spa Marvel, pH values as high as 8.4 were promoted, which does in fact relieve some of the effort that would normally be required to maintain pH within CDC-recommended ranges.  What concerns me here is that I am not aware of of any science telling us that the CDC’s “chlorine vs pH” recommendations do not have to be followed when Spa Marvel is in the water, which is essentially what I was told.

The CDC is very clear:  pH values above 8.0 result in poor chlorine effectiveness, and that has been an objective fact established for many years, so I’m calling foul ball, here.   There are a great many spa owners who are able to keep their pH levels within the CDC recommended ranges,  although it is common to target the high end of this range (7.8) to make life easier.  I just can’t endorse a deliberate effort to target a pH that is higher than the CDC recommends.

Claim Status:  Busted, but I’ll gladly change this when I see the science telling us that the CDC is wrong or hasn’t accounted for the presence of enzymes and surfactants. 

  • Spa Marvel conditions hot tub water for sensitive skin. People with eczema and psoriasis love using Spa Marvel as it often improves their condition.  If there is medical evidence that the combination of enzymes and surfactants relieves these conditions, I’ll call this one “plausible” as I’m not a doctor and I can’t disprove the anecdotal stories.   Based on my experience, however, I suspect that many of these conditions would also be greatly relieved with proper water maintenance protocols without Spa Marvel in the picture, so its not clear to me what the singular contribution of Spa Marvel itself actually is, apart from proper  maintenance that naturally removes the sources of irritation — such as biofilms, very high Calcium levels,  high pH, etc..  Show me medical evidence that the ingredients in Spa Marvel help these conditions and I’ll support this claim.

Claim Status:  Plausible, but I would also point out that Spa Marvel hasn’t provided any medical evidence or studies, or even a testimonial that these conditions are improved  by the addition of Spa Marvel when the spa is otherwise well-maintained.  

  •  this natural spa solution allows you to eliminate and greatly reduce many of the chemicals used in spa water treatment. Spa Marvel is as close as you’ll ever get to that chemical-free spa water feeling.  I just don’t get this.  Spa Marvel didn’t do any of this for me, because I had already established a minimalist approach to maintaining my spa.  Perhaps the operative word is “feeling” here.  I saw no benefit,  I measured no result, a felt no difference in my water, and in fact Spa Marvel was an addition to my regimen, not a reduction.  My opinion is that this is one of the claims that pushes people to reduce their chlorine ppm levels and become blissfully unaware that they are just lucky, but not safe. Its emotion, not science.

Claim Status:  Busted.  Its not the Spa Marvel itself that allows you to return to minimalist protocols, it is your knowledge and willingness to do it.  Of course, if someone tells me they are using a properly maintained minimalist spa already, and they can feel the difference of Spa Marvel in the water, then I won’t argue the point.   The problem I have, here,  is the perception that lower levels of chlorine are now possible with Spa Marvel in the water, and that’s just not true . The way to achieve the chemical-free water feeling is to eliminate biofilms with a real purge product (see “minimalist spa maintenance” above where I describe the use of Ahh-some), and then follow with a minimalist approach to spa chemicals that is still capable of killing the pathogens that can harm you.  Enzymes don’t kill bad guys;  Chlorine does.


  • Softens and moisturizes skin.  So does my wife’s hand cream, but that doesn’t mean I want it in my spa;  This sounds like a cosmetics commercial.   The thing that softens and moisturizes skin is proper maintenance and adopting a minimalize protocol, avoiding dangerously high levels of chlorine, high pH, or the dry “hard water feeling” caused by very high calcium or tired, old, water that should be drained.    Again, if the enzymes, combined with the small amount of TSP (a surfactant) by themselves and in addition to a minimalist protocol,  makes someone’s skin feel better, then I won’t argue the point. I just think that’s a lot of money to spend on water “conditioning” when you can achieve the same results yourself.

Claim Status:  A marketing claim that cannot be proven.  If someone can define what “softens and moisturizes” means, and prove that the ingredients in Spa Marvel actually does this, apart from proper maintenance protocols, I’ll change this to “true”. 

  • Is gentle to skin, hair and bathing suits.  This is likely true, but so is a minimalist protocol.  The gentleness comes from proper maintenance and the right chlorine levels.  But I acknowledge that enzymes and TSP are gentle, for sure.

Claim Status:  True.  The ingredients in Spa Marvel are gentle.  

  • Absentee spa owners can expect clear and clean water after being absent for months at a time.  I disproved this claim in grand fashion for my own spa, which is outdoors and subject to wind, dust and such.  So, I’m calling foul on this claim because of the way it is stated.  I was an absentee spa owner and I expected clear and clean water after being absent for only 7 days, but when I returned, my water had gone terribly bad.  I even shocked with chlorine before I left!   So, no, this claim is false.  What is probably true, however, is that spas kept indoors in controlled, germ-free environments would probably last .  But as a pmuch longer than mine did.  As a practical matter for those who’s spas are outdoors — I say no way.  The enzymes do not kill bad guys — they only compete for their food supply.  So, under real conditions (especially outdoors) you will not be able to rely on an enzyme to keep your water from going bad.  I acknowledge that there are probably anecdotal stories of long-term absences, but given my results and the mechanism at work I would say “don’t rely on this”.  There are better ways of achieving this goal.

Claim Status:  Busted,  because not all absentee owners can expect this.  In a controlled, indoor, germ-free environment I can see the possibility of this working better than my results however.    My own assessment is that this provides no practical advantage for outdoor spas subjected to normal elements such as wind and dust.  “Your Mileage will vary”, as they say.  Anecdotal stories work for some but not others.

  • Is easy to use. One bottle of Spa Marvel treats your hot tub water for 3 months with regular use; and 1 month in a swim spa.  This is true; I found it very easy to pour the bottle into my water, for sure.

Claim Status:  True

  • The all natural formulation provides for the ideal spa solution for the eco-conscious spa owner.  I personally do not think Spa Marvel is the ideal solution for the eco-conscious spa owner because in my tests the product did not make any contribution to environmental consciousness.  I used the same chemicals that I always do and  in virtually the same amounts.  So, if you want to be environmentally conscious, all you have to do is adopt a minimalist protocol and you can even avoid the plastic bottle that Spa Marvel comes in.  If you want to extend your drain interval and dump your spa water onto your lawn less often, there are more effective maintenance products that will help you achieve this.

Claim Status:  I disagree.  Marketing is Marketing, and just because they said so doesn’t make it true

  • Spa Marvel natural hot tub treatment provides for water so soft and clean you won’t feel the need to shower after using your spa.  You can achieve this same goal without Spa Marvel so I call this one false.  Your are, in fact, adding two new things to your water and your skin:  The Enzymes themselves, and the TSP surfactant.  neither of these are harmful and as I have mentioned before:  If you like the feel on your skin (and you are honest and not succumbing to the placebo effect)  then go team go, I say.  But a minimalist protocol for spa maintenance will do the same thing in large part.  As water ages, and Total Dissolved Solids increase, you will start to feel like taking a shower after exiting your spa, but pouring Spa Marvel in to your water doesn’t slow this process down.  In fact, after two months of using Spa Marvel, my spa water already feels like it needs draining.

Claim Status:  Another Marketing claim that cannot be proven.  Minimalist spa maintenance regimens achieve this in grand fashion without Spa Marvel 

  • Makes owning a hot tub hassle free.  The interesting thing about this claim is that it can be achieved without Spa Marvel entirely.  Its not the Spa Marvel itself that makes owning a hot tub hassle free, it is the attention to detail and your willingness to adopt a minimalist protocol for spa maintenance that is also effective at killing bad guys — not just competing for their food supply.

Claim status:  Overstated:  I have to acknowledge that the enzymes in Spa Marvel do something — its just that they create a dangerous false sense of security because they do not kill the bad guys.  Moreover, hassle free spa maintenance does not require Spa Marvel to achieve.


Whew!  that was long.  But so is the amount of marketing verbiage used to promote Spa Marvel.  The above is simply my good-faith opinion based on my experimental results, which  I will change in a heartbeat when I see the evidence to do so.    Spa Marvel is not “bad” in the sense that it introduces something you don’t want into your water — on the contrary it does do “something” good  (compete for the bad guys’ food supply).    I just find the product to be over-sold, over-stated, and the slippery marketing language to be dangerously misleading.  The product didn’t provide any of the purported benefits in my tests, but the reader should note that  I had no problem to solve and I wasn’t looking to Spa Marvel to  provide any improvement in my spa.  Had the product made my skin feel better I would have reported such, but it just didn’t,  so  I just don’t see the point of it.   Could I clean my filters less often?  perhaps, but thats not a problem for me.  My overall conclusion is that the vast majority of Spa Marvel’s benefit claims will come from adopting a minimalist protocol for spa maintenance anyway.  The principle ingredients — enzymes and the TSP surfactant — didn’t help me.  Beyond that I will re-state some of the more important concerns I have:

  • I believe it is dangerous to tell people they can run pH as high as 8.4 where chlorine effectiveness is “poor” according to the CDC, but I’ll change this tune when I see the evidence that the CDC is wrong.  I  believe this claim is based on the conclusion that “chlorine has less work to do” or that “surface tension is lower” with Spa Marvel in the water, all of which leads to the mis-information that one can roll with less-effective chlorine (due to high pH).  You can’t.  The bad guys do not magically die easier with Spa Marvel in the water!
  • The “use less chlorine” claim is a complete “don’t care”.  There is no benefit to equipment longevity because you aren’t changing the actual ppm chlorine levels in your water just because Spa Marvel is in the water.  Using fewer granules of chlorine to achieve the same ppm level in the water might save you money — and it might actually slow the increase of Total Dissolved Solids in your water, but beyond that this claim is a big nothing-burger.
  • I think the product is dangerous because it gets people to think they can run their spas at lower chlorine levels — simply because they have been conditioned to believe that Spa Marvel is a wonderful elixir that allows fewer chemicals, when all this stuff does is put a surfactant in your water and compete with the bad guys for food (without actually killing them).  Spa Marvel has very skillfully obfuscated the difference between “use less chlorine over time” and “use your spa with a lower ppm  chlorine level”, which I consider to be mis-information.
  • The marketing language is just so slippery I cannot bring myself to trust the product.  I have de-mystified it to the point where I understand what it is doing, and find that it doesn’t benefit me.  The benefit of reducing the load on my filters is probably real, but I can save $20/month just by cleaning them, so to me the cost of the product just isn’t worth it.
  • The “extended absence” claim is probably true for indoor, well-controlled environments — or even outdoor environments where there is no wind, dust, and no bad guys in the air.  But for real outdoor situations like mine it just doesn’t work.
  • If someone tells me that that their skin feels better simply by adding Spa Marvel is to the water (when the spa is properly maintained in the first place) then I say go for it.



6 thoughts on “Spa Marvel review – the enzymes

  1. Love your simple approach to water care! I basically do the same thing (based on some of the experiments you’ve written about) with a few adjustments. I add 50 PPM boric acid at fill which is supposed to help stabilize the PH (and it does seem to help with that). Also, I use a saltwater chlorine generator which basically is my automatic way to add chlorine so I don’t have to do it when I don’t use the tub or am on vacation. I add bleach after use to account for the chlorine demand of the soak. Thanks for your posts.

  2. Hi Doug. Regarding your comments about shocking the tub with chlorine. You mention that you bring the chlorine levels up to 30 ppm. And a steady rate of chlorine should be between 1 to 3 ppm. My question is does the Chlorine level dissipate from 30 ppm to 1 to 3 ppm on its own ? Or do I need to empty the tub again so that we can reduce the chlorine level? FYI. I have a salt tub.

  3. Hi Brent — yes I will bring chlorine levels up to 30 ppm when I am purging — and that water goes into the ground when I drain. While it is true that chlorine dissipates on its own it would take several days for well-maintaned spa to dissipate 30ppm down to 3ppm . I also advocate for steady state Chlorine levels higher than 1-3ppm because biofilms have been shown to grow in those conditions (see foundational materials on the Hot Tub Home page). If you are already at 30ppm you will probably need to drain — or wait a long time 🙂

    In a pinch you can use ordinary hydrogen peroxide to neutrialize chlorine

  4. Hello,
    We just got a “previously loved” hot tub. We are very green to taking care of it. My husband has been in 3 times and he broke out in little bumps and itches like crazy!
    What are we doing wrong so this doesn’t happen?

    1. Dear confused owner 🙂 previously loved hot tubs are notorious petri dishes. sounds like you need a good “purge” — you can use all the right chemicals and still get hot tub rash! what normally happens here is that biofilms accumulate and theres a myth out there that a good shock or de-contamination procedure (with very high chlorine shock) fixes these things, when that is often not the case. I would suggest this; get a jar of “ahh-some”, and purge your tub per label directions as I describe on this site. be prepared to purge several times — I have personally coached people into purging more than 10 times, which means (yes) filling the tub 10 times!

      unfortunately, tubs that sit for any length of time (including brand new tubs like mime) will grow bilfilms, and the only way to get rid of that is to purge with ahh-some. nothing else comes close

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