Greetings Hot Tub enthusiasts
Those who are familiar with my work know that I have spent large amounts of time and water, testing various purge products. This post is not about that - it is instead dedicated to the little-known fact that biofilms can apparently survive and even grow in the presence of chlorine.
Did you know that that?
One of the references cited in my original work (see below) describes a controlled experiment with the simulated bather load, water filtration and turn-over rate of a swimming pool. Their laboratory model was "challenged with a bacterial load and synthetic bather insult, formulated to represent urine and perspiration". The purpose of this work was to study the effectiveness of two common sanitizers, chlorine and biguanide. In a rather stunning statement in their abstract, the researchers describe that "biofilm was able to accumulate on coupons and in the filter systems of reactors treated with either 1–3 mg/L free chlorine or 10 mg/L polyhexamethylene biguanide (PHMB) (emphasis mine). The abstract goes on to describe that the biofilm accumulations were considerably attenuated compared to the control, but the astonishing thing is that they accumulated at all -- in the presence of 1-3ppm FC and in the normal bather load of a swimming pool.
This connects a lot of dots, and demonstrates that the high bather load, higher water temperatures, and more widely fluctuating sanitizer levels of a Hot Tub present an even more hospitable petri dish for bad guys. We should be even more careful than the pool side of the house, not only with regular shock treatments but with regular purges designed to break up and release biofilms. I used to be an advocate of letting your purge results dictate how often you purge, but now I am an advocate of purging upon every drain. full stop. its so easy to dose with ahh-some right before you drain, and the work you go through, wiping everything all those surfaces, will remind you of the importance of your work.
Also -- let this portion of the paper's abstract keep ringing in your ears: biofilm accumulates in the filter, even with chlorine present! (emphasis mine). This is why it is so important to "purge" your filters too, at the same time as you purge your tub. I cut a piece of PVC pipe just the right length to hold all of my filters, to keep them from clogging up the skimmer weir.
"death to biofilms..."
Controling biofilms in spas and hot tubs - PART 1
Evaluation of disinfectant efficacy against biofilm and suspended bacteria in a laboratory swimming pool model by D.M Goeres, T Palys, B.B Sandel, and J Geiger
Those who are familiar with my work know that I have spent large amounts of time and water, testing various purge products. This post is not about that - it is instead dedicated to the little-known fact that biofilms can apparently survive and even grow in the presence of chlorine.
Did you know that that?
One of the references cited in my original work (see below) describes a controlled experiment with the simulated bather load, water filtration and turn-over rate of a swimming pool. Their laboratory model was "challenged with a bacterial load and synthetic bather insult, formulated to represent urine and perspiration". The purpose of this work was to study the effectiveness of two common sanitizers, chlorine and biguanide. In a rather stunning statement in their abstract, the researchers describe that "biofilm was able to accumulate on coupons and in the filter systems of reactors treated with either 1–3 mg/L free chlorine or 10 mg/L polyhexamethylene biguanide (PHMB) (emphasis mine). The abstract goes on to describe that the biofilm accumulations were considerably attenuated compared to the control, but the astonishing thing is that they accumulated at all -- in the presence of 1-3ppm FC and in the normal bather load of a swimming pool.
This connects a lot of dots, and demonstrates that the high bather load, higher water temperatures, and more widely fluctuating sanitizer levels of a Hot Tub present an even more hospitable petri dish for bad guys. We should be even more careful than the pool side of the house, not only with regular shock treatments but with regular purges designed to break up and release biofilms. I used to be an advocate of letting your purge results dictate how often you purge, but now I am an advocate of purging upon every drain. full stop. its so easy to dose with ahh-some right before you drain, and the work you go through, wiping everything all those surfaces, will remind you of the importance of your work.
Also -- let this portion of the paper's abstract keep ringing in your ears: biofilm accumulates in the filter, even with chlorine present! (emphasis mine). This is why it is so important to "purge" your filters too, at the same time as you purge your tub. I cut a piece of PVC pipe just the right length to hold all of my filters, to keep them from clogging up the skimmer weir.
"death to biofilms..."
Controling biofilms in spas and hot tubs - PART 1
Evaluation of disinfectant efficacy against biofilm and suspended bacteria in a laboratory swimming pool model by D.M Goeres, T Palys, B.B Sandel, and J Geiger