Controlling Biofilms in Hot Tubs and Spas – part 2


Controlling Biofilms in Hot Tubs and Spas part 2

Summary and Conclusions 




With the previous work behind me,  I now had the confidence that, of all the products I tested thus far,  Ahh-Some was the most effective for the purpose of releasing contaminants trapped in pipes, equipment, and filters.  Based on the sanitizer demand test results, I personally concluded that biofilms were most certainly part of the released material, at least of the first experiment.   For the second experiment — the amount of released material that had accumulated over six months, left by four other products,  was so great and so convincing I decided it was not necessary to prove the existence of biofilms because doing do would not change anything:   I resolved to treat any Ahh-some release as the label directions indicate —  as if it contained biofilms.  That meant combining the Ahh-some purge with an elevated chlorine level.

The last portion of the experiment (filters) revealed an interesting result:  what is the nature of the material released by Ahh-Some that could not be released by a filter degreaser product?  Since Ahh-Some does not make any claims for being a degreaser, I concluded (although without proof) that biofilms must have been released from my filters.


As for the other four products I tested:




At best, they accomplished very little, if anything, and I remain astonished at what they don’t do.  The data show that Silk Balance “Clean Start” and Aquafinesse “Spa Clean” are not even worth the value of their own packaging, as they had absolutely no effect on the hidden contaminants in my spa.  The SeaKlear product appeared to produce a small result, at least with known bad water, but its effectiveness paled in comparison to that of Ahh-Some.  Natural chemistry’s “Spa Purge” also produced a visible result in my experiment, but the amount of material it released was so small that I consider it to be ineffective as well, compared to Ahh-Some.  It did, however, produce epic amounts of foam:  Over eight times as much as Ahh-Some (see Reference below for my calculation)**.

As for the original questions raised in PART 1, I now have satisfactory answers:

Q:  Are filters immune to contaminant or even biofilm accumulations when proper maintenance procedures are followed, sanitizer demand remains low, and filters are regularly cleaned and degreased?

A:  Emphatically, no!  My results show that contaminant material does accumulate within the filter media itself, even with properly maintained water and use of a traditional degreaser product. I now clean my filters with a combination of Ahh-Some and a traditional degreaser product , or simply place them into the spa vessel itself during the purge.  From now on I treat my filters as if they harbored biofilms and I will always “purge” them with Ahh-Some.

Q:  Is clear water and normal sanitizer demand sufficient evidence that biofilms cannot be present?

A:  Its true that these conditions are strong evidence that biofilms are not present.  However, even though my water was maintained well, Ahh-Some released very large amounts of contaminant material that the other products did not touch.  This result, combined with what we know about chlorine-resistant biofilms and biofilm recovery/regeneration, suggest that biofilms could very well have been present as part of the total released accumulation.   For me personally, the presence of any amount of contaminant accumulation means there is a chance of biofilm contamination, as the former could become a food supply for the latter.  I would not want to enter my spa knowing that a live culture of Legionella, for example, might have found safe harbor underneath a chlorine-resistant layer of biofilm that had recovered or regenerated within my pipes or within the pleats of my filter.

To be sure, once a pathogen enters the water itself, the kill rates of chlorine and bromine sanitizers protect the bathers from waterborne disease, assuming the right concentrations are present of course.  Once could argue, then, that hidden biofilms could be benign, even if they are present.  However, this is hardly comforting, given that (for example) legionella is transmitted via the mist produced by jet aerosolization.  Spas maintained with alternative, non-Halogen based sanitizers are especially vulnerable to the risk of water-borne pathogens, whose kill rates have not been established.

Q:  What are the signs that biofilms may be forming in the Spa?

A:  I’ve seen enough evidence to suggest that biofilms could potentially form (or recover/regenerate in the pipes, equipment, and filters) even when good maintenance practices are followed and when the water is clear.  However, there are some important signs of biofilm accumulation:  Aside from visible evidence in the water itself (cloudy, hard to maintain), the single most important sign, rarely mentioned by Spa stores or understood by private users, is the sanitizer demand test:  For chlorine/bromine users, one rule of thumb is that the decay rate over 24 hours should be 25% or less, without ozone present (ozone eats chlorine but produces bromine).  Rather than depending on an absolute number, however,  a better approach is be to purge regularly with Ahh-Some.  How often do mean by “regularly”?  I purge my spa on every drain, and as long as my purges release material, I know that I am not purging too often.  If you want to play chemist, you can always establish a baseline “sanitizer demand”  for your own spa, and then to watch out for an upward trend–   An upward trend in sanitizer demand, even when the water is otherwise clear, is compelling evidence that something is consuming the sanitizer, such as dirt, organics from nearby trees, a stray spider, or biofilms.

I also suggest that conditions marginally favorable to biofilm accumulation may be present more often than some owners are willing to admit. The presence of warm water at rest, short durations of localized low (or even zero) sanitizer levels, and the presence of biofilms partially dislodged from a previous purge could create an environment where biofilm regeneration can quickly occur.  This is why it is important to purge regularly.    As the literature shows, biofilms are pretty smart.

Q: Can a chlorine shock treatment remove or deactivate biofilms?

A:  I do acknowledge the effectiveness of industry best practices for decontamination, which usually involve 50-100ppm doses of Chlorine, and variations of the “SLAM” (Shock Level And Maintain) procedure.  Should we use such techniques to control biofilms? I’m not so sure.  Note that, prior to my first (SeaKlear vs Ahh-Some) experiment, I shocked my Spa with a dose of 50ppm Chlorine for one hour, but my sanitizer demand remained high until I purged with a Ahh-Some.  Would 100ppm for 2 hours have been more effective? Should I have SLAM’ed my spa for days?   Perhaps, but  My conclusion is that the more effective approach to biofilm control is to combine a moderate level of chlorine with the Ahh-Some purge. 

Q:  What concentration of chlorine is appropriate for an Ahh-Some purge?

A:  My recommendation is to dose to about 30ppm  FC,  which is the practice I have been following.  I used to recommend 20ppm but because many spas have fair concentrations of CYA I’m taking a “better safe than sorry” approach.  Frankly, 50ppm won’t hurt your equipment, due to the short duration of the purge.  My point is that with an ahh-Some purge you don’t need to hit your equipment with crazy long and high concentrations of chlorine!   

Use regular, pure unadulterated bleach from the grocery store, for the purge (do not use dichlor).   Unless you have a high accumulation of CYA in your spa (more than a few weeks’ use of dichlor), 30-50ppm should provide sufficient kill efficiency, even if Burkholderia pseudomallei is part of the release (study the CDC information below).  With CYA present, however, this concentration is probably not high enough to kill the parasite, Cryptosporidium, which is a particularly nasty, chlorine-resistant “bad guy”  —  that problem would require a full-on decontamination procedure at 100ppm FC,  even after purging with Ahh-Some.    In any case, the benefit of using Ahh-Some is that instead of attenuating embedded  biofilms “in their place” with extraordinarily high chlorine concentrations, you can dislodge and release them instead into a lower chlorine concentration for a complete kill — without stressing your equipment.

Q:   Why are some products so successful in the market place when they do so little?

A:   I am convinced that marketing is a powerful tool, and that consumers want to believe that something is working, especially if they have paid top dollar for it.    I would also suggest that with bad water and bad maintenance, most any product could produce an impressive result, especially if large amounts of foam are involved and.   While I personally would like to see less of it, I will note that the amount of foam produced by Ahh-Some was commensurate with its effectiveness – one is left with the impression that its foam production is a consequence of its cleaning action.   This was not the case with Natural Chemistry, for example.  Its foam production was so great that I was left with the impression that it contained specific foaming agents just for visual impact!  In actuality it may simply be a marginally-effective enzyme combined with as much surfactant-type ingredients as commercially possible.

Q:  Can biofilms be present in brand new Hot Tubs and Spas as delivered by the manufacturer or local store?

A:   Without question, Yes. Manufacturers and owners may choose to ignore the evidence, but science and my results strongly support the conclusion that wet testing at the factory, followed by subsequent time delays associated with transportation and storage (sometimes under warm weather conditions), can in fact result in delivery of a contaminated spa.  Manufacturers may incorporate a good shock or decontamination policy as part of their wet testing programs, but sanitizers decay over time, and such procedures do not always protect the consumer.   Manufacturers and retailers are faced with a dilemma:  if a complimentary purge is performed on the customer site, then competitors will use this as a marketing tool to convince customers that “their” spa does not need this – perpetuating the myth that biofilms are not a problem.  Conversely, if the manufacturer purges at the point of assembly, then transportation and storage time can still contribute to biofilm accumulation, as my own experience confirms.  On the other hand, if the local dealer purges immediately prior to customer delivery (the best option for consumers), the optics of delivering a brand new, shrink-wrapped spa are compromised.

Progress in this arena will only occur when consumers are educated and the industry as a whole demands more attention to the biofilm issue, or when one or more manufacturers figure out a way to promote biofilm protection as a competitive advantage.   Until then, here are my personal recommendations:

1.  ALL new spas, upon factory delivery to the home, should be purged with Ahh-Some, drained, and re-filled before they are used for the first time. This is to protect against organic contaminant growth that has occurred during storage and transit.

For more information regarding formation of biofioms during storage, please see my blog post about spas in storage.

2.  ALL used spas, whether they come from a store, from a storage shed or  if they are a private party purchase — and  by all means if it “came with the house” — all such spas should be purged with Ahh-some several times until no new material is released.  This may take two purges or it may take more. My own personal spa (delivered with biofilm contaminants) took 2 purges to be successful, and I have personally coached others where more than 2 purges were required.  Each purge should be accompanied by a 50ppm chlorine shock, which itself can be neutralized with ordinary drug store peroxide right before draining (if desired for environmental protection). Use the Ahh-Some/Chlorine mixture to wipe down all surfaces.

3.  Once the spa is clean (per above steps) my experience suggests that you should purge the spa every time you drain and refill at least to start with.  Purging every time is as simple as dosing with ahh-some (follow label directions) and chlorine right before you drain.   Of course, after you establish a regular habit of purging every time, but you see that the purge does release any new material and you have no unusual sanitizer demand, you can consider purging less often.   In any case, I recommend purging at least every other drain or approximately six months.  Remember that biofilms are nasty creatures with the mind of their own and they DO regenerate very quickly and with vigor, when they are disturbed but not completely eradicated.


for a real-world shoot-out between ahh-some and another product, please see part 3 of this series



Reference Information:

* Here is the CDC information showing Chlorine kill rates for various organisms

**  the amount of foam produced by Ahh-Some, in 30 minutes, was 70% of what Natural Chemistry produced in 5 minutes. (30min/6min)/.7) = 8.57, or “over eight times”)


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