Dichlor/Bleach

[sstrahan7@msn.com]

I have read on another forum about using bleach instead of dichlor after your CYA levels reach about 20-30ppm. I am nervous about putting anything in my tub not recommended by the manufacturor/dealer, being I paid a lot for it and don't want to mess anything up. Is there anyone on this site that can vouch for this method? Is it safe? The dealer was having me dump in a lot of dichlor and MPS the first couple weeks I had the tub up and running to kill off chloramines, now my CYA is at 150ppm. I also read that MPS can  read as CC, so maybe my high chloramine level was inaccurate?  I know you can't believe everything you read/hear so it is confusing for a newbie to know who to believe, what method to use. Some people say getting the chemicals right is easy but it's been a frustrating couple of weeks for me. I have been adding 2 tablespoons MPS before I get in, and depending on the chlorine level adding a small amount of dichlor after use. I'm wondering if I should switch this to bleach?

[H823Putt]

Do a search on Chem Geek. He has posted plenty of times on here about the use of bleach. Very imformative.

[sstrahan7@msn.com]

AHHH, ok, sounds like I may be "beating a dead horse" here! Don't know why I didn't see those threads when I searched before. It's still confusing as some people say it is OK and some say never do it. Oh well, I guess there can't be an easy answer for everything. I will continue searching the forum and see if I can come up with anything

[gadfly]

You won't find a lot of information on using bleach, other than a handful of devoted internet "experts".  My issue with those bleach advocates, is that much of it is theoretical.  Some of those writers don't even own a hot-tub, and are extrapolating information from their pool experiences.  Others have had success in their own tub, and assume it works in all locations/situations.

Dichlor and bromine are the "standards", and work well for most people, regardless the other variables.  I suspect that manufacturers and dealers recommend them, because they are simple and straightforward, easy to apply, and relatively safe.  I would suggest working with your dealer to fine-tune your procedure first.  After you get some experience, then you can experiment to come up with a procedure that works for you. For the record, I don't think there is anything wrong with using bleach, and I doubt it would cause any problems in warranty, unless you use it incorrectly... but the same would be true dichlor.  I also wouldn't worry about CYA levels until the numbers get much higher.  If you dump your water every 2-3 months, it is not an issue for most people.

Search for an old post about "Chas Rule", and the benefit of dumping your first fill, relatively quickly.

[chem geek]

It has never been "theoretical" for pools since chlorinating liquid is nothing more than stronger bleach and has been used in swimming pools for many decades (more details about bleach as well as other grocery-store equivalents to pool/spa chemicals are in this post).

It is no longer "theoretical" for spas either since the Dichlor-then-bleach method (or similarly, pure CYA first then bleach ongoing method) has been used and proven in spas since January, 2007 after I first proposed it (waterbear and probably others had mentioned using bleach prior to that, but I first described building up the CYA level some first in January, 2007).  People started trying the Dichlor-then-bleach method and found that their water would last about twice as long as usual between refills and that the water quality was still better when they changed it compared to Dichlor-only.  We have also not had the hot tub itch/rash/lung incidents that were being reported previously (from a variety of systems, not just Dichlor-only), but the sample size is way too low to draw conclusions about that.  However, initially we didn't understand how powerful the higher aeration and hotter temperature in a spa caused carbon dioxide to outgas faster causing the pH to rise too quickly in some spas (this can cause scaling if the CH is too high and the pH is not lowered).  We then had the Total Alkalinity (TA) level significantly lowered to around 50 ppm which helped with most spas, but some still had pH rise issues.  Eventually we proposed using 50 ppm Borates in the spa (as with ProTeam® Gentle Spa or boric acid) which combined with a low TA level solved the pH rise problem or made pH manageable for all spas.

Most of the Dichlor-then-bleach users report in at PoolSpaForum.com, some report in at Trouble Free Pool and some here on this forum.

The chlorine/CYA relationship is chemical fact known since at least 1974 (see this paper and the Chlorine/CYA Relationship section in this post).  It is true, however, that the spa industry chooses to keep things simpler (and more profitable) by recommending Dichlor-only since the use of Dichlor is net acidic when accounting for chlorine usage/consumption so helps keep pH in balance when the TA is at the higher recommended levels.  It is also a single chlorine product to use and far more profitable than bleach.  Also, as a powder/granular, there is less chance of spilling/splashing it in concentrated form on clothes during dosing which would ruin them by bleaching them (though there is also very expensive lithium hypochlorite powder/granular that is essentially the same as bleach except it's more concentrated and is not a liquid).

Now that it's been over 4 years with hot tub users using this method, I would say the main downside is the same as that of Dichlor-only which is that one needs to add chlorine regularly, every day or two, to the spa.  For people who soak every day or so, this is not a problem as they simply add the appropriate amount of chlorine immediately after their soak.  However, for people who only soak once a week or so, bromine is more convenient since bromine tabs in a floating feeder can keep a residual sanitizer level in between soaks.  Some others have started using saltwater chlorine generator systems for the same reason though if they do not add any CYA initially (either via pure CYA or by using Dichlor as an initial shock) then their active chlorine level will be too high yet you don't hear spa dealers complaining about that because most simply don't understand the chemistry.  We'll see how long it takes for spa cover manufacturers to start voiding their warranties when using such systems even though the solution is simple -- namely adding some CYA to the water after a refill.

Also note that one of the main problems with most sanitizer systems is that heavy spa users tend to not use enough oxidizer after their soak to oxidize bather waste (mostly urea and ammonia from sweat and urine), be it chlorine or MPS.  A rough rule of thumb is that in spas without ozonators, every person-hour of soaking in a hot (104ºF) spa requires around 3-1/2 teaspoons of (nearly pure) Dichlor, 5 fluid ounces of 6% unscented bleach or 7 teaspoons of non-chlorine shock (43% MPS).  Spas with ozonators will tend to require half these amounts if one soaks every day or two, but in spas that are less frequently used (say once a week or so) an ozonator can roughly double chlorine demand in between soaks.  The usual no-bather-load chlorine demand is an FC drop of around 25% over 24 hours in the first months after a fresh refill; with an ozonator, this can be 50% (though depends on the strength of the ozonator relative to tub size).

Richard

[gadfly]

...It is no longer "theoretical" for spas either since the Dichlor-then-bleach method (or similarly, pure CYA first then bleach ongoing method) has been used and proven in spas since January, 2007 after I first proposed it (waterbear and probably others had mentioned using bleach prior to that, but I first described building up the CYA level some first in January, 2007)... We have also not had the hot tub itch/rash/lung incidents that were being reported previously (from a variety of systems, not just Dichlor-only), but the sample size is way too low to draw conclusions about that...

You may have been the first one to write a "paper", and make it a big deal about it in this little corner of the internet, but to say you were the first to propose it, seems a reach.  Others have been using/ both dichlor and bleach for years... my spa dealer recommended to his customers way back in the 90s (primarily to manage pH, and to a lesser concern managing chlorine/CYA competition).  I also question your statement that you "first described building up the CYA level".  That has been known long before 2007.  There have been recommendations to manage its level, for years.

To attribute any change in "hot tub itch/rash/incidents" to your "work" is an even bigger stretch.  First of all, most of those incidents are not fully investigated, and the true cause has usually not been identified, much less the resolution.  Second, the number of reported events is tiny, so to draw a conclusion that any change is related to few postings on hot-tub boards is not even psuedo-science.  Third, how many people do you think actually use your method?  My guess is the number is at most in the low three digits.  Compare that to the number of people who use dichlor or bromine only.  I think if there is a truly a change in incidents, I think there are likely other factors that would deserve more credit, than your internet "papers".

I have always been curious about your qualifications.  You obviously have a chemistry background, but what is it?  How much hands-on experience do you have with hot tubs in the field?

This said, I think you do serve a purpose on these boards, and have helped some people manage their hot-tubs, and I hope you continue to help people.  It is only when the hubris gets a level like this, I object. 

[chem geek]

I knew that some people were talking about using bleach instead of Dichlor, but I had never heard of anyone proposing using Dichlor for a short time to build up CYA and then switching to bleach nor figuring out how to maintain pH in a hot tub when using only bleach (after initial Dichlor) by significantly lowering the TA level and using borates (though these techniques for managing pH were not new and had been used in pools, though not usually with as low a TA).  So yes, if there were others proposing that, then I wasn't the first -- I just didn't know that (this issue also came up in this forum earlier in this thread).  And from what you are saying it sounds like it wasn't from an understanding of the chlorine/CYA relationship and how a buildup of CYA could reduce disinfection and oxidation rates, but rather was to balance the net acidity of Dichlor by going back and forth in usage (which would still build up CYA, but more slowly, so really isn't the same as Dichlor initially and then switching to bleach-only).  By the way, the pool & spa industry normally says that Dichlor is pH neutral, but where else have you heard about chlorine usage/consumption being acidic (as I describe technically in this post)?  Though it's pretty obvious chemistry, almost everyone in the pool & spa industry says that bleach and chlorinating liquid are high in pH (which they are) implying that they will cause the pH to rise a lot if you use them which isn't true if the TA is low enough and that Dichlor, being close to pH neutral, will keep the pH constant (which it won't unless the TA is high enough and there is enough aeration).

As for the chlorine/CYA relationship in pools, a lot of credit goes to Ben Powell of The PoolForum (and PoolSolutions) that had a chlorine/CYA chart that I believe was first to do so, though maybe you know of others who proposed that relationship earlier.  He came up with that mostly from his own experience managing pools and then later got some chemistry confirmation from Wojtowicz and then later on from me (especially with why the FC/CYA ratio is proportional to the active chlorine level as I describe in this post and from my Pool Equations spreadsheet).

I wasn't saying I was the only one talking about CYA buildup from Dichlor or other stabilized chlorine.  That has been known for a long time though mostly talked about for pools, not for spas, though I do believe I was the first to put it into easy-to-understand ratios independent of pool/spa water volume or concentration of product as in the following chemical rules (again, others may have done this, but I've never seen it before):

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm.

As for hot tub rash/itch/lung incidents, I said it was a small sample and one couldn't draw conclusions from it, but it WAS the main reason I started focusing on hot tubs in terms of Dichlor-only and CYA buildup (prior to that I was mostly focused on pools on other forums).  I did personally contact some of the users (via PM and E-mail) to get more details such as what was discussed with their doctors and how it was diagnosed even though I didn't always post such info in some cases due to privacy concerns.  The side benefit with Dichlor-then-bleach of extended time between water changes was an added benefit, but not my main concern when I got started looking at it.

I do not work in the pool or spa industry and am not a chemist.  I graduated from U.C. Berkeley over 30 years ago with an A.B. in Physical Sciences which I did essentially equivalent to a double-major in Physics and Chemistry since I took the courses that way, but they didn't have such a double-major because of too many overlapping math courses.  I had a 3.8 GPA with 12 A+'s (counted as 4.0).  However, after getting an M.B.A., I went into software engineering and management for my career.  I have had a pool for around 8 years, but no spa/hot-tub.

(continued in next post)

[chem geek]

(continued from previous post)

I wouldn't put much stock in some of the information provided by pool/spa industry people -- their experience, yes, but not when they drift into recommendations based on faulty chemistry.  The manufacturers have a lot of profit incentive to guide information a certain way.  I personally bought up every copy I could find of the Chemistry of Water Supply, Treatment and Distribution book at my own expense (some copies being very expensive as there weren't many available) and sent it to members of the APSP-11 committee as well as those at the CDC, NSPF and elsewhere.  Then I contacted the publisher, the editor, and one of the authors and obtained permission to reprint the O'Brien paper.  I was trying to get the FC and CYA levels tied together for recommendations for what became the ANSI/APSP-11 standard, but to no avail.

Another example of where the industry sometimes gets it totally wrong is in what they say about breakpoint chlorination and shocking with chlorine to get rid of Combined Chlorine (CC).  They say to raise the FC level to 10x the CC level and that anything less will not achieve breakpoint.  This is just plain wrong.  The 10x ratio comes from chlorine oxidation of ammonia, not of CC, and chlorine and ammonia are measured in different units.  Chlorine is measured in ppm Cl₂ while ammonia is measured in ppm N, the ratio between these being around 5.06.  For chlorine oxidation of ammonia, it takes 3 chlorine for every 2 ammonia, so a 1.5 to 1 ratio which with the chlorine and ammonia units becomes 7.6 to 1.  Because of some side reactions and needing some more chlorine to get over the "hump" to form dichloramine (a 2 to 1 ratio), the actual chlorine needed is 8-10 so the 10x rule was born.  While the rule is correct for chlorine oxidation of ammonia, it's the wrong rule for CC not only because CC is measured in chlorine units, not ammonia units, so there is no factor of 5.06, but also because CC already has 1 of the 1.5 (net total) chlorine attached to it as monochloramine.  Even if one looks at monochlorourea which likely shows up as CC, the needed ratio is around 3 to 1, not 10 to 1.  And finally, nothing gets "stuck" if you don't use enough chlorine -- you can just add more and pick up where you left off.  So a higher FC level will oxidize faster and may get rid of some CC faster, but there is no magic 10x.  So even industry experts who are real chemists sometimes make mistakes and perpetuate incorrect information.

So I'm sorry I came across as being the first to propose something when others apparently proposed Dichlor-then-bleach before I did.  If that is the case, and if your spa dealer recommended using both Dichlor and bleach, then why did you write "you won't find a lot of information on using bleach, other than a handful of devoted internet "experts"" seemingly discounting this method by putting experts in quotes when you knew that there were in fact others who had also proposed the same thing (or at least something similar where bleach was used)?

[gadfly]

Sorry, I must have ADHD... when a response runs over into a second post to get the point, I lose interest.  I will have to wait for another time to digest it, I have to work tomorrow, and have a busy week.  I didn't peruse your latest entry, but saw enough to know your GPA and number of "A+"s, from 30 years ago.    Your first post in this thread had me thinking of Al Gore inventing the internet.  This one seemed more like the guy who slips in to posts his Mercedes, how successful his business is, and that he once considered starting up a spa store... and uses that to imply that he is an expert on all things "spa". 

You gave me a nice laugh, to end up the weekend, have a good week. 

[chem geek]

Rather than tearing down people's personalities or backgrounds that you question and then when given an answer tear them down again, I suggest you stick with the science and facts relating to hot tubs or water chemistry which until your post questioning my knowledge and credibility is what I've tried to do.  The (mostly) pool sites The PoolForum and Trouble Free Pool have helped literally tens of thousands of pool owners by sticking with facts, not just information that the pool & spa industry tout (are they the experts in your opinion?).  Better methods were developed by observation, experiment, and understanding the science (when possible).  Pool and Spa Forum was trying to start to do the same thing, but for whatever reason none of these spa sites (including this one) has even close to the same traffic as the pool sites I mentioned.

[Jet Sitter]

gadfly - Seems to me that chem geek responded in earnest to your questions.  You say you don't have time to read his posts but nonetheless take a cheap shot at him anyway.  Although you seem to question his background in my mind you are the one who lacks credibility.

[D1Dennis2009]

Gadfly,

I hate to say it, but you sound like you are a real jerk, don't ask for feedback if you don't like to invest time in the answers..! I'm sure that I will get a spanking for laying it out in a way that you can understand, you should apologize to Chem Geek. Just my opinion, and it may be worth "less than yours" in the end.

[soak-king]

.

[Dr. Spa™ Ret.]

Some people just have difficulty with big words, and more than two sentences.