Hot Tub Serum

Greetings Hot Tub Enthusiasts,


This is part 7 of the series, dealing with controlling Biofilms in Spas and Hot Tubs.  Other articles in this series are found here:


Those who have followed my work know that I have a proclivity to exposing junk products, especially the snake oil in the Hot Tub industry, while highlighting useful ones.  My work thus far has concentrated on purge products, and the surrounding information/education important for understanding Biofilms in residential Hot Tubs and Spas (see references in PART 1).

In this article, I take a notable departure from my previous work, and review a product that isn’t a purge product per se, but a maintenance product.  There is no “shoot out” here;  just results of my experimentation thus far with a product from the makers of “Ahh-Some”, known as “Hot Tub Serum”.  


Why do we need both “Ahh-some” and “Hot Tub Serum”?

Those who have followed the “Ahh-Some” product on the forums know that it’s primary active ingredient comes from a family of compounds known as “Quaternary Ammonium Cations”, sometimes referred to as “QUATs”.  Ahh-some is a gel product containing a very high “QUAT” concentration —  the formula has been shown known to break through the protective fat layer of biofilms.   My own experimentation confirms t “Ahh-Some” is far superior to any other purge product on the market, at the time of this writing. 

With this background information regarding the “Ahh-Some” product itself, I was intrigued to find out that the active ingredient  in “Hot Tub Serum” is approximately 9% “QUAT”, according to the label.  I’m not a chemist so I cannot comment on the differences in the active ingredients themselves, other that the fact that they are different “QUAT” concentrations.  However, this similarity piqued my interest in the use of such a formula as a maintenance product. 


What does this stuff do?

The primary claims of the “Hot Tub Serum” manufacturer involve improvements in water clarity and in ease of water maintenance.  This is interesting, because those of us with impeccable water maintenance skills (Read the forums on “dichlor then switch to bleach” method) are usually reluctant to adopt a new product claiming to improve upon our own perfection.  I decided to be honest with myself and realize that I wasn’t 100% perfect 100% of the time, and decided to put this product through a couple of scenarios “near the edge” of good water maintenance.  


test #1:  The “oops”

My first test was to deliberately simulate a “less than perfect” maintenance scenario — such as a vacation or similar circumstance where the sanitizer level is allowed to reach zero.  To set up the test, I used my (Bromine) hot tub normally, on one occasion, but did not add any new sanitizer to oxidize the bather waste.  This approach guaranteed that the bad guys would have a chance to grow, and resulted in a very nice cloudy soup of “water gone bad”.  

This is a scenario that happens, for example, when you haven’t shocked the tub strong enough prior to leaving on vacation, and normally requires a SLAM (“shock level and maintain”) treatment and 1-4 days to recover,  before the spa is usable again.  This time, however, I used a “modified SLAM (Shock Level and Maintain)” process — I added the recommended dose of “hot tub serum” (per label directions) and a “shock level “of Bromine but didn’t do the “maintain” part   (it turned out not to be necessary). In other words, by the time my sanitizer level had dropped to safe levels, my water was clear again.  This told me that the use of Hot Tub Serum was in fact better than a traditional process of attenuating biofilms with a prolonged high concentration of chlorine.    

I must acknowledge at this point that my results are empirical and “preliminary”, in the sense that they represent data from two experiments.  Nevertheless, my empirical observations are important and form the basis for future experiments, which I will use to “let the data lead”. 


First result

Due to my personal schedule there was no way for me to establish a “baseline of contamination” (control), so it was physically and statistically impossible to actually measure the rate at which the the two processes “consumed” contaminants to produce a usable spa.  I simply observed that Hot Tub Serum  cut the the process approximately in half — what would normally require 2-4 days  using traditional SLAM now took 1-2 days.  Apparently, the QUAT ingredient is an effective supplement to traditional sanitizer (chlorine or bromine):  After all — the active ingredient found in Hot Tub Serum is similar to (but in lower concentration) that found in Ahh-Some itself, the latter of which has already achieved EPA registration for its biofilm kill properties!  This was a promising result, which led to a more scientifically-governed experiment


test #2

With the previous observation I was now in a position to more carefully determine the performance of “Hot Tub Serum” – but this time, my goal was to simulate a more common scenario among those of us who are proud of our water maintenance skills —  the sanitizer decay rate in otherwise “normal” appearing water.   Here again, forming a controlled experiment was very difficult, but I established one that would at least be of interest:  I would perform a sanitizer decay rate test before and after using the Serum!  To accomplish this, I waited until my water was near the end of its drain interval — and then measured the bromine decay rate under no load.  This experiment was performed during the summer months during which I did not use  my spa at all — I reserved its use, for nearly four weeks, solely for the purpose of measuring decay rate.  

After establishing a “baseline” of bromine decay rate I decided to treat my spa with the recommended dose of “Serum” for two weeks.  During this time ,I  held the sanitizer level at normal levels, i.e. 2-4 ppm Bromine, so that I was not SLAMing my spa at all —  but the spa was under “no bather load” of course (no use of the spa for this time period).  To my astonishment my data showed that a two-week treatment with Hot Tub Serum did appear to improve the Bromine decay rate.  


Second Result


The graph shows a result at “hour 48” that is interesting to forum watchers:  before treating with “Serum” my Bromine level baseline (see the orange line in the above graph) decayed  from 5ppm to 1ppm  over 48 hours.  This is equivalent to a “24 hour decay rate” of 40% — a bit high, compared to the standard rule of thumb which suggests that the 24-hour decay rate should be closer to 25%.  This is clear evidence that organic contaminants are consuming the sanitizer — the remedy for which is typically a purge with ahh-some.  Instead, I treated with the Serum.   

After two weeks of Hot Tub Serum, I repeated the sanitizer decay test ,which produced the blue line in the above graph.  Note the “after Serum” treatment  shows a decay of 5ppm to 2ppm, over  the first 48 hours, which is equivalent to a “24 hour decay rate” of 30% — much closer to the accepted rule of thumb.  The other important point is that the Serum treatment resulted in a much more gentle and “stretched out” decay rate.  You can see that I stopped measuring after 132 hours  (over 5 days)!   incidentally, my ozone generator was disabled during these tests.  

How many spas can start at 5ppm and still measure .5ppm Bromine after 5 days?  The result illustrates that the shape of the decay curve is much more important.  To illustrate, consider the time period between 48 and 132 hours, which demonstrates a “24 hour decay rate” of only 20% “After Serum”.  



These data are far from complete and are not statistically valid — but they do represent a result that needs to be validated with further experimentation.  Hot Tub Serum appears to be an attractive product that not only accelerates the SLAM process,  but could very well eliminate the need for SLAM.   While my results are both preliminary and empirical, I am reminded that Hot Tub Serum “has my back” every time I measure zero Bromine and my water is still perfectly clear

As a practical matter, I have been experimenting with Hot Tub Serum for a couple of years now, and find it to be extraordinary.  It has made water maintenance easy, and is especially useful when sanitizer levels drop into the low single digits.  Better yet, I know why — my sanitizer decay rate is a long a gentle slope.


Please also see PART 8 of this series, for additional information re:  Hot Tub Serum



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