liqued bleach in your hot tub

[Vinny]

Richard,

THANKS! Sorry to ask all those questions with you on vacation at Yosemite!

You were not the person who said not to use dichlor, it was another person. The neutralizing affect I was talking about was the PH effect of using bleach - no need to explain.

Some misconceptions were cleared up. At this point I still will be on dichlor but at least I'm aware of how Pseudonomas are introduced and not "grown" in a tub - I believe that most tub owners have that same misconception.. Once I use up my tub of dichlor I will try the bleach routine. The concept that bleach is PH neutral was not believable but you explained it to me.

Thanks for taking the time out to explain!

Vinny

 

[NWMNMom]

Just had someone ask me, is there a procedure for "converting" from bromine to bleach in a spa/hot tub? Do they have to completely drain and refill or can they just add bleach and continue to monitor their PH, ALK, CH and FC/CC levels? Thanks.

 

[JasonLion]

To switch from bromine to bleach you pretty much need to drain and refill. Adding chlorine will only reactivate the bromine, which hangs around for a long time. Eventually, if you stop replacing it, the bromine will go away, but that takes so long that it is impractical.

Switching from chlorine to bromine is much simpler, just add bromine.

 

[NWMNMom]

Thanks. I'll let him know. He says he can never seem to get the bromine levels right and heard I use bleach in my pool. I told him two different things but MAYBE you could use bleach.

 

[Vinny]

Just remind your friend that if it's a new spa that using bleach may void the warranty. Of course the only way the dealer would know is by your friend telling the dealer or if the dealer tested for CYA and there was none.

 

[chem geek]

Even in a BBB hot tub, it's a good idea to have some CYA in it, though not much -- perhaps around 20 ppm. So using Dichlor for around a week or so will get you to the 20 ppm CYA and then you can switch to bleach. The CYA will help reduce odors from combined chlorine and from chlorine itself and will also have your swimsuits last longer. I believe that the bacteria that causes hot tub itch will be conservatively killed at 4 ppm FC with 20 ppm CYA. All other common bacteria are readily killed at far lower levels of disinfecting chlorine.

Without the CYA, I can understand the greater concern for corrosion of the heater. Now I wouldn't try explaining all this to the dealer, but using Dichlor initially should address the core concern regarding the voiding of the warranty.

 

[Vinny]

Richard,

Why would 0 CYA be a concern for the heater? I thought during our discussion that the corrosive end was not a concern (I am assuming the salt content). There are numerous people (Canada) who use lithium chlorine and it doesn't contain any CYA. I do know that it has lower active chlorine but 4 PPM is the same whether you use lithium or bleach or dichlor (at lower CYA readings).

Also, the way I dose the tub is to use chlorine after soaking to kill the bacteria (got that from the microbiologist). Soaking 24 hours later will give you close to 0 PPM chlorine, no chlorine smell and my black bathing suit is still black after 2 years!

Vinny

 

[chem geek]

Vinny,

The disinfecting chlorine concentration which is the concentration of the active form of chlorine, hypochlorous acid, that does the actual disinfection and oxidation of organics as well as oxidizing (corroding) metal, is far far lower in a pool or spa with CYA in it. With modern heat exchangers (using titanium instead of copper), the risk of damage at FC levels below 5 ppm even without CYA is probably low, but the chlorine in a spa with no CYA is still about 20 times as strong and corrosive as in a spa with a CYA of 20 ppm (it just works out that the ratio of disinfecting chlorine is roughly the CYA ppm, when the pH is near 7.5). This same strong chlorine oxidation also wears on swimsuits, skin and hair, and outgasses more chlorine and smelly monochloramine and other disinfection by-products.

My wife swims in an indoor pool with an average of 2 ppm FC and no CYA and her swimsuits (as well as others who use the pool) are ruined after just one winter of 5 months -- the elastic is shot and there is some sign of fading (and these are fade-resistant swimsuits). In our own pool with 3-6 ppm FC and 25-30 ppm CYA during 7 months of summer, there is no sign of degradation except very slightly after 4 seasons of use. The reason for this difference is the CYA since the indoor pool has from 7 to 22 times more disinfecting chlorine so wear on swimsuits that much faster.

You have found a way around this problem of ultra-high disinfecting chlorine by doing the shocking after you get out of the tub and entering in the next time with essentially no chlorine in the water. Though that will prevent smell and fading swimsuits, it also does not protect you from bacterial growth from the time the chlorine went away including the time in the tub itself. It also does not protect you from the fecal-to-oral contamination that can occur from you or others in the tub (realistically, that's the main concern, not general bacteria present on skin, etc.). Though it is true that the bacteria will not spontaneously form and will have been killed during the shock, bacteria are everywhere and they double in population in 15 minutes to an hour. So after 24 hours, one bacteria will turn into from over 16 million to over 8x10^28 (well over a trillion trillion) though clearly will be limited at some point by nutrients in the water.

So another way to handle the problem is to use Dichlor initially to get the CYA up to around 20 ppm and then keep a chlorine level of around 4 ppm including when you are in the tub. The CYA will keep the disinfecting chlorine level down which will reduce the smell and any degradation of swimsuits. You will still probably want to remove the hot tub cover for 5 minutes before using the tub, just to air it out a bit as there is still some build up of chlorine smell, but it will continue to outgas rather slowly.

The same principles should also be applied to indoor pools, but they are not, and is why I believe there are so many reports of asthma and respiratory problems with indoor pools. It can't just be the air circulation nor the lack of sunlight as the differences are orders of magnitude. I believe the biggest factor (in addition to those mentioned) is the lack of CYA in indoor pools. This patent, ironically from Bio-Lab which was bought by Chemtura and make the BioGuard and SpaGuard brands, talks about how glycoluril slows the production of trihalomethanes (Example 7) and the gas-off of both chlorine and inorganic chloramines (Example 4). Glycoluril is a compound very similar to CYA except that it even more strongly binds to chlorine, but chlorine is still released as needed (i.e. it's an equilibrium, not a totally one-sided reaction). I've been trying to get some athletic organizations and other indoor pool users to see if CYA helps with the health problems (and other issues), but am fighting the uphill industry mantra of "CYA doesn't matter; only Free Chlorine matters".

Richard

 

[Vinny]

Richard,

I never knew that CYA has a "buffering effect" on chlorine, I only knew it protected the chlorine from UV deteriation. I guess then people who don't use dichlor in the tub (lithium) may have more problems with corrosion or swimsuits. Does CYA of 20 PPM have the same effect at 8 PPM chlorine or would 40 PPM CYA be needed to get the same effect? I ask because it seems that people in Canada don't have dichlor readily available and use lithium mostly unless on bromine and I would think it can affect some heaters as they probably aren't all made the same.

My disinfection routine is based on that microbiologist's posting. He gave a very indepth answer about it, kind of what you post on here, and he tested his tub as I said. I don't have that capability but 1 case study with someone who "knows" what he is talking about was good enough for me to try. Since then there are a lot of people who use his method and all seem not to have any problems with bacteria in their tub unless it gets away from them, more case studies IMO. Basically, if you soak for 45 minutes and get out, whatever bacteria that was on your body will have doubled 3 times (I have no clue how many that would be); you dose for 3 PPM chlorine ( you say 4 PPM) reading 20 minutes later and it has done the job. Since you effectively killed the bacteria and will have a chlorine residue, the bacteria can't get started until the residue is too weak to do anything. This optimally should be done daily, he claimed to do it every other day if he didn't use the tub but is using ozone and N2 as supplimental sanitizers. Shock weekly or every other week with 10 PPM chlorine to get resistent bacteria. I never thought about the fecal to oral contamination but I do not dip my head under water and the most people in the tub is 4 (my family) but it typically is only me. I do add more chlorine when more people use the tub up to about 6 PPM. I also add chlorine before and during if I have company over to make sure the water is biologically safe and of course shock after. At what point bacteria wise is water considerd biologically unsafe?

One thing I should note is that I usually have a chlorine residue 24 hours later even starting at 3 PPM and I know that I can get only about 48 hours from my last dose or my tub gets cloudy from bacteria. Even with 3 months of dichlor use my tub behaves the same way so I know it is killing "normal" bacteria. I have experimented different ways on my tub and with my current ozonator setup I will get another day if it runs 24/7 and the same holds true when I used the spa frog and the water was new, up to 2 months old. I have not tried the frog with 24/7 ozone. I'm still fence sitting about ozone. I even tried only putting 1.5 PPM chlorine in the tub but after about a month it was too little for me to feel comfortable - no room for mistakes.

Maybe too much info but I wanted to explain it.

Thanks for taking the time!

Vinny

 

[Guest]

Just remind your friend that if it's a new spa that using bleach may void the warranty. Of course the only way the dealer would know is by your friend telling the dealer or if the dealer tested for CYA and there was none.

Not necessisarily true, For example Arch Chemical only sells calcium hypochlorite based products for spa use in their HTH brandand these would not have CYA in them. They do not offer dichlor for spa use in the HTH line but do offer it in the Brilliance brand. Also, as you noted above lithium hypochlorite is often sold for spa use. Dichlor is a popular choice for spa chlorination because it is fast dissolving but it is by no means the only choice.

 

[chem geek]

Thanks for the explanation. And yes, people who don't use Dichlor in the tub AND enter the tub when there is Free Chlorine would likely have swimsuits degrade more quickly. These days with titanium heat exchangers, I think there's less risk of corrosion, but if you've got an older copper heater then the risk may be higher but I don't know how high -- I just know it's higher by a factor of around 20 (since the oxidizing power without the CYA is about that much higher).

The 20 ppm CYA with 4 ppm FC is similar to 40 ppm CYA with 8 ppm FC and is similar to 0.2 ppm FC with no CYA. All of these combinations (at a pH of 7.5) have the same amount of disinfecting chlorine (hypochlorous acid). Remember that this recommendation of mine was based on CT values of 30-50 for Pseudomonas aeruginosa, the bacteria that causes hot tub itch, as I described in this post so you can see the source links I used -- not a lot of data for that bacteria -- there's much more data for E.coli and common heterotrophic bacteria.

As for the CYA buffering effect on chlorine, even buffering against pH changes, look at this post where I show graphs of the traditional industry chlorine chart without CYA and the true chart with CYA where you can see how CYA not only holds chlorine "in reserve" but also buffers the small amount of disinfecting chlorine (hypochlorous acid) against pH changes.

I understand what the bacteriologist has measured and in fact most bacteria will be killed a lot faster than 20 minutes. The CT values (chlorine concentration in ppm times time in minutes) for 99% (2-log) kill is 0.08 for most bacteria so even chlorine with CYA at standard levels in pools will kill 99% in about a minute or two. It's the 99.99% (4-log) kill rate for hot tub itch with the CT of 30-50 that implies taking 20 minutes if you've got around 4 ppm FC with no CYA. That's probably what he was talking about. My calculation of 4 ppm with 20 ppm CYA was to have a kill rate at 50% that was faster than the reproduction rate of 15 minutes, but this calculation was on the edge and assumed the CT numbers were lower at the higher temperatures in the hot tub (as is typical with CT values). His not using CYA certainly would kill most anything except Cryptosporidium.

The only issue I have with his approach is when the chlorine residual drops low near zero. If that happens too long before you get into the tub, then there's time for bacteria to grow (and it's true that such bacteria would have to "drop in" from somewhere, such as from the edges of the tub). That's one of the risks. The other is the fecal-to-oral route I talked about. If there's no chlorine in the tub when you or others get in, then fecal bacteria could splash into your mouth (I know it's gross, but we're talking about why chlorine residuals are important), not just skin bacteria which are fairly innocuous. With all the jets and bubbling, you don't have to dunk your head to get exposure. The primary reason for residual chlorine when people use pools or spas is to kill this fecal bacteria before it can reach your mouth, nose, eyes and ears, whether it's your own bacteria or someone else's.

Quite frankly, the risks I'm talking about above are low risks. It's just that you never know when you'll be the unlucky one where a bacterial population causes a problem for you because you've got some sort of cut or sore and the hot tub itch then becomes a problem, etc. It's just that with residual chlorine before and during your soaking will virtually guarantee that there won't be bacteria nor other pathogens except for the real hearty ones of Giardia and Cryptosporidium cysts (which are protozoan cysts).

The standard cutoffs for being bacteriologically unsafe are a heterotrophic plate count (HPC) of > 500, Non-Fecal Coliforms or Fecal Coliforms of more than 1, and Non-Coliforms > 200. But these counts refer to specific sample sizes, plate sizes, etc. and not total bacterial populations in water. Basically, the goal is to not have any measurable number of coliforms (bacteria that live in warm-blooded animal intestines).

Anyway, you noted that you always have some residual dose of chlorine so you are right that you are probably fairly safe. By the way, water normally is CLEAR even with large bacterial populations. You can't use cloudiness as an indicator. It's large algae clumps that make water dull, then cloudy and then green. Bacteria usually aren't visible unless they form large colonies as on agar gels, but in water you usually can't tell it's bacteriologically unsafe.

Richard

 

[Vinny]

Just remind your friend that if it's a new spa that using bleach may void the warranty. Of course the only way the dealer would know is by your friend telling the dealer or if the dealer tested for CYA and there was none.

Not necessisarily true, For example Arch Chemical only sells calcium hypochlorite based products for spa use in their HTH brandand these would not have CYA in them. They do not offer dichlor for spa use in the HTH line but do offer it in the Brilliance brand. Also, as you noted above lithium hypochlorite is often sold for spa use. Dichlor is a popular choice for spa chlorination because it is fast dissolving but it is by no means the only choice.

Waterbear this is out of my spa manual:

4 - Sanitizers: Sanitizers are used to destroy bacteria and other germs in the water. Only 2 sanitizers are used in spas, chlorine (Sodium Dichlor) and Bromine (Hydrotech or Lonza). Without the use of a mineral system or an enzyme, the preferred level of sanitizer is between 2 and 3 ppm.

Although that statement is not necessarily true in Canada, they seem not to be able to get dichlor and some manufactures or dealers even recommend trichlor. I realize that there are different forms of chlorine but if anyone told a dealer they used bleach, cal hypo, trichlor or anything else that can put chlorine into a spa other than the recommended chlorine - the warranty may be voided. Do you think that a dealer would replace a part under warranty if you didn't follow their or the manufacture's instructions?

My belief of HTH chemicals is that for the Walmart buyer (only place that sells HTH by me) that doesn't know about the different chemicals will buy it and wonder why they have problems. I have had people on tub forums wonder why their tub is cloudy as they are using chlorine. I asked what chlorine they use and it's the HTH brand. I can't speak of how much calcium a teaspoon would put in but add it up. I also have heard people complain about the roughness on their tub and it's from the calcium depositing on the surface with high PH. I know a lot of people don't really test their water but IMO using Cal Hypo for a tub is a definite bad thing unless your willing to really test the water. Out of the tap I could use cal hypo until my calcium reached 150 to 200 PPM and then stop but I doubt the average spa owner knows that or cares to know that.

 

[Vinny]

Richard,

I ran out of time this morning but I want to again say thank you for explaining this all to me. Unfortunately, the microbiologist doesn't post anymore so I don't have someone who understands this at a higher level than I do to learn from.

We do sometimes go in the tub around 48 hours after santizing and we haven't had a problem yet. I know that clarity isn't a indicator that the tub is biologically safe. I'm also thinking that between the chlorine and ozone off gassing that the bacteria under the cover is being somewhat neutralized and combne it with a residue 24 hours later the bacteria doesn't have enough time to get to "lethal" levels by the time I go in again. I did think though that the cloudiness is from too many bacteria in the water and not algea since the tub is covered 99% of the time but I guess not.

I think his point of 20 minutes is to make sure that enough chlorine is put into the tub to be able to get a 3 PPM reading 20 minutes later. His concern was the bottle saying add 2 teaspoons to 500 gallons, you add it and it's not enough for the biological load.

You've answered a lot of variables. I don't go into public spas and for the most part I don't have too much company so killing the hot tub itch bacteria is not a concern; I originally thought that the bacteria in the tub would turn into that bacteria some how. I never thought about the fecal to oral contamination but I would think it is a low risk in a large size hot tub (400 gallons) and the short, 30 to 40 minutes, soaking time. I can't say that we are protected by chlorine when we (my family) soak in it but I do add chlorine to the tub when company comes over "just in case". Of course with a CT of 50, the hot tub itch bacteria will survive a longer time as the CYA increases.

Although as a pool owner I am aware of the CYA to chlorine issue many hot tub owners really don't have a clue. Other than hearing about a few people contracting the itch, most people don't have bacterial problems. Funny thing is most people who get it is from new tubs. For most hot tubbers having high CYA isn't a big deal, I guess it's a good thing that most bacteria is easily killed.

As for cysts, I will be experimenting with a higher output ozonator with a longer run before it goes into the tub. Right now I am not impressed at all with the ozone system my tub currently has. A new system won't help with the cysts when I'm using the tub but afterwards hopefully it will. I do plan on trying bleach but I'm thinking it will be more of a hassel than adding 2 to 4 teaspoons whenever it needs it.

Thanks again!

Vinny

 

[chem geek]

Unfortunately, the microbiologist doesn't post anymore so I don't have someone who understands this at a higher level than I do to learn from.

That's too bad, because I was hoping to be able to contact him directly since I'd like more CT data on the bacteria that causes hot tub itch (I really dislike having only one source) and figure he might know where to get it.

I know that clarity isn't a indicator that the tub is biologically safe. ...
I did think though that the cloudiness is from too many bacteria in the water and not algea since the tub is covered 99% of the time but I guess not.

Bacteria CAN cloud the water, but usually don't unless their numbers get huge. That was my point. Cloudiness occurs when there are enough cells clumped together to significantly diffract/diffuse light. You can have a lot of individual cells of either bacteria or algae and still have clear water. Technically, there's really nothing wrong with being in water with algae. It's just a plant and isn't going to hurt you. It's just unsightly and most people don't like it AND if algae can grow than bacteria (most of which are much more easily killed than algae) can certainly grow and THAT is the problem.

I don't go into public spas and for the most part I don't have too much company so killing the hot tub itch bacteria is not a concern; I originally thought that the bacteria in the tub would turn into that bacteria some how. I never thought about the fecal to oral contamination but I would think it is a low risk in a large size hot tub (400 gallons) and the short, 30 to 40 minutes, soaking time. I can't say that we are protected by chlorine when we (my family) soak in it but I do add chlorine to the tub when company comes over "just in case". Of course with a CT of 50, the hot tub itch bacteria will survive a longer time as the CYA increases.

The CYA won't increase if one just uses Dichlor for the first week after a fresh refill to get to around 20 ppm and then switches to bleach after that. It's only when using ONLY Dichlor (as with the "Vermont" method) that the CYA increases and then hot tub itch can thrive. You are right that if the bacteria that causes hot tub itch doesn't get introduced into your pool water, then it won't be there, but it can get in there from skin or swim suits so shocking after having guests come over would be wise. Also, keep in mind that the hot tub itch bacteria may in fact be in a lot of spa water, but most people aren't affected by it -- you need to be more sensitive or have open cuts, sores or rashes.

Although as a pool owner I am aware of the CYA to chlorine issue many hot tub owners really don't have a clue. Other than hearing about a few people contracting the itch, most people don't have bacterial problems. Funny thing is most people who get it is from new tubs. For most hot tubbers having high CYA isn't a big deal, I guess it's a good thing that most bacteria is easily killed.

Yup, it's a very good thing that most bacteria are easily killed. Just keep in mind that all of these issues with disinfection are PROBABILITIES. It takes a combination of factors or events to have a problem. By disinfecting with sufficient chlorine, one just cuts the probability to near zero. It's not that improper disinfection has the probability go to 1 (i.e. will definitely happen).

As for cysts, I will be experimenting with a higher output ozonator with a longer run before it goes into the tub. Right now I am not impressed at all with the ozone system my tub currently has. A new system won't help with the cysts when I'm using the tub but afterwards hopefully it will. I do plan on trying bleach but I'm thinking it will be more of a hassel than adding 2 to 4 teaspoons whenever it needs it.

The protozoan cysts of Giardia and Cryptosporidium are only introduced into pool water from someone who has these and typically has diarrhea. So for public pools and spas, these pathogens are a bigger concern, but for your spa it's far less likely to be an issue than hot tub itch or even easier-to-kill bacteria so I wouldn't worry about it.

Richard

 

[Vinny]

Richard,

So you are familiar with the "Vermonter" method - he is the microbiologist that I am talking about. He wrote that because of the people who come to the forum he participated in and asked "how do I use chlorine". He doesn't delve into the chemistry portion of using dichlor, just the method of what to do and if I remember correctly - why to do it. He runs his tub on dichlor and as I said he also uses Nature 2 and ozone in his tub but truely believes that chlorine is the effective ingredient.

Vermonter owns his own lab and he had tested his own water along with other "regulars" water during an experiment which I think was with monthly enzymes. He really does preach running a biologically safe tub. In his professional opinion and testing - even with 3 months worth of dichlor use the tub is biologically safe. When I did ask him if he tested CYA his answer was no.

I guess if you would like to see what he wrote I can send it to you via a private message.

Vinny