Dichlor (The Dirty Little Secret)

[Nitro]

Since I continue to get attacked here, I'd like to clear the record.

My first post is nothing but FACTS, and completely unbiased. The reason for the "Dirty Little Secret" title is because the industry continues to ignore these facts. I even give the real (and legitimate) reason the industry initially pushed Dichlor. It is because using ONLY Unstabilized Chlorine (Bleach) is too strong. i.e. Using ONLY Dichlor is better than using ONLY Bleach. However, if you read the posts that followed, you will see that the "Bleach is Bad" argument immediately started coming from some other members. I then gave a VALID argument for using the Dichlor/Bleach method as opposed to using only Dichlor. Then we continued to get bombarded with Bleach is bad, it's too dangerous, it's difficult to use, it's too complicated, Lithium Hypochlorite is better than Bleach etc. All of which are very thin. The only real disadvantages to using Bleach are, you need to keep track of CYA before switching to bleach, and you'll need to keep your TA lower. However, the advantages are MANY.

I agree with Chem Geek with just about everything except one thing. I believe the Dichlor Only method causes many more problems than is currently known. Who's to say if a person with No(Low) Chlorine would not have had the problem if they were able to shock the tub to a proper level (FC=10, CYA=20) on a regular basis. I don't think it's possible to accurately estimate the percentage of problems caused by No(Low) Chlorine vs High CYA, unless you measured everyone's CYA who had a problem, and graphed it. The Bottom Line is: The higher CYA gets, the lower the effectiveness (sanitation and oxidation) of the Chlorine. So it doesn't take a genius to figure out, the higher your CYA the more water problems you'll have. That doesn't mean you WILL have problems. It just means your chances of having water problems get higher as your CYA raises. Keep that in mind when determining how often to change your water.

Regardless of the real percent of High CYA problems, one thing IS clear. The Dichlor/Bleach method does have advantages over using Only Dichlor. And for SOME members on this board to dismiss them is a real shame. For the record, I don't think everyone using Dichlor should switch to Bleach. However, I do believe they should know about the risks of having high CYA. As I have said MANY times, the Dichlor/Bleach method is not for everyone, but some are saying it's not for anyone. I don't think Dichlor is as bad, as they seem to think Bleach is. Which is unusual to me, because there are plenty of regular everyday folks (who are not chemists or mathematicians, and who do not obsess over their tub) using the Dichlor/Bleach method who find it very easy to use. It seems the only people who have a problem understanding this method (and its benefits) are "experts".

Carry on.  

[Tman122]

Don't change anything.  What is being discussed is something affecting a smaller number of people.  Just out of curiosity, do you have an ozonator or are you using Nature2/Frog or other metal ion system?  How often do you soak each week (number of soaks, how many people, how long per soak)?

I was trying to be funny Chem Geek, but when I did have a tub (currently moved to a country lake home and use sauna) that is the routine I used. And to answer your questions. Yes I used an O3 generator but it only ran for 4-6 hours per day during filtration. I was sceptical on its effectivness except to maintain already sanitized with dichlor water between soaks. Yes I used a Nature 2 stick and again, to maintain dichlor sanitized water between soaks cool but to sanitize.....not for me. Me and my x-wife soaked 1-3 times per week for 30-45 minutes. I maybe soaked longer once in a while. We had friends over a time or two a month and a few big gatherings a year.

[chem geek]

I was trying to be funny Chem Geek, but when I did have a tub (currently moved to a country lake home and use sauna) that is the routine I used. And to answer your questions. Yes I used an O3 generator but it only ran for 4-6 hours per day during filtration. I was sceptical on its effectivness except to maintain already sanitized with dichlor water between soaks. Yes I used a Nature 2 stick and again, to maintain dichlor sanitized water between soaks cool but to sanitize.....not for me. Me and my x-wife soaked 1-3 times per week for 30-45 minutes. I maybe soaked longer once in a while. We had friends over a time or two a month and a few big gatherings a year.

Thanks for the info.  It's good that you had an ozonator because if you didn't, then you would probably have needed to add more like 3-1/2 to 5-1/4 teaspoons of Dichlor after each soak to handle the bather load and have residual FC leftover since 2 teaspoons (without an ozonator or supplemental oxidizer) would only roughly handle one person (not two) soaking for 30 minutes (at 100-104F).  If the shocking was weekly with 2 tablespoons of Dichlor or 2 ounces of MPS, then that would have roughly caught up though "late" unless you had higher FC even during soaks.  At around 2 times per week, the CYA (without shocking with Dichlor) was only increasing by around 30 ppm per month (assuming 2 teaspoons of Dichlor in 350 gallons) which is a slow increase so you could go quite a long time before a refill of the water would be needed.  If shocking was with Dichlor (instead of MPS) weekly, then CYA would increase 77 ppm per month.

Since it is very clear that the number one reason for sanitation problems is not having enough sanitizer, the primary reason for this is that people (without an ozonator) aren't using enough oxidizer for their bather load and it seems that this is something that isn't talked about very much.  Using a "per person" amount of Dichlor helps, but it also matters how long one soaks and if the water is very hot which it usually is (100-104F).  Yes, there are variations of the amount of sweat, but it's nice to have a rough rule as a starting point.  Then one can make sure that a residual FC is being seen before the next soak to be sure.  At a minimum, people need to use a DPD (pink/red) chlorine test to measure FC and not just total chlorine (TC), so they shouldn't be using the OTO (yellow) chlorine test (or test strips, some of which are not very accurate); the FAS-DPD "count the drops" test is even better, though more expensive.

The issue of CYA, therefore, is primarily applicable to those who have higher bather load -- that use a hot tub daily, for example.  One person soaking for 30 minutes every day and adding 2 teaspoons of Dichlor to a 350 gallon tub would be raising the FC around 4 ppm and over one month the CYA would rise a little over 100 ppm.  It is this situation, or those with even higher bather loads (more people or longer soaks) and especially those without N2 or an ozonator that is primarily what the Dichlor-then-bleach method is trying to address so that one does not have to replace their water once a month to ensure consistently high sanitation levels.

In commercial/public spas (which generally recommend against use of CYA completely, as shown here, though virtually all states limit both pools and spas to a maximum CYA of 100 ppm), there is a Water Replacement Interval (WRI) formula as follows:

WRI (days) = (1/3) x (Spa Volume in U.S. Gallons) / (Number of Bathers per Day)

The formula does not account for soak time but apparently assumes around 20-30 minutes average.  If I use the example of one person soaking for 30 minutes which (without an ozonator) uses 2 teaspoons of Dichlor in 350 gallons, then the WRI is 117 days.  The CYA level at the time of needed water replacement would be around 420 ppm, but again remember that it is recommended to not use stabilized chlorine (e.g. Dichlor) in commercial/public spas (which I believe to be too extreme -- a small amount of CYA would be less harsh on skin and swimsuits while still providing reasonable sanitation).  People using Dichlor-only find that their water gets more dull and sluggish after 3-4 months of daily use (one person soaking 30 minutes every day) while with Dichlor-then-bleach the water remains near its original refill quality and if desired one can go longer between refills.  This is more of an issue with very high bather loads such as 2 people soaking for an hour every day where the standard WRI would be 30 days.

Richard

[tony]

I started using bleach in my pool along with trichlor about four or five years ago.  I started with bleach (along with dichlor) in my spa about two years ago after five years with dichlor or a combination of dichlor, N2 or Frog and ozone.  In my situation being a daily user, bleach after using dichlor to reach the proper CYA level has worked best.  It is not the easiest and it is not for everyone, but it is certainly not difficult.  I now use chlorine only, no minerals, no ozone.  I shock weekly with MPS because I like how it works.  I use the small 24 oz bottles of regular Clorox which are easy to handle and are as small as my dichlor container.  Every other week I may need to add a tablespoon of dry acid for pH but thats about it.  I don't use borates or anything like that and I keep it simple.

The advantage to bleach, IMO, is of course no CYA and the lack of TDS.  The water does not bog down.  It has the fresh fill feel for months.  Even though my water was always crystal clear with dichlor, it would slowly go downhill.  At my four month water change, there was always that...there's nothing like fresh water...realization.  Not so with bleach.

I am not one to recommend bleach to anyone, but you need not fear it either.  While it may not be for everyone, it works, works well and is probably as pure a chlorine as is practical to use.  

[sonofsail]

Leave it to an Optima owner to put up the best post on this subject.  

[Vinny]

Since I continue to get attacked here, I'd like to clear the record.

Nitro,

It's no doubt you are up on water chemistry.

But, IMO you were "attacked"  bacause you came onto this forum and like I said before really have no history here. What are your credenditals? Are you in the pool or spa industry? Things to that nature. I believe you were also "attacked" by the dealers that were insulted by what you were saying. It's like me giving out stock market advice and saying nothing about who I am ... I could be Warren Buffet or I could be nobody or I could be an unknown proficient trader - unless there's some history about me nobody knows.

You are also giving a little bit of "wrong" information out as well. My comment about adding baking soda and raising PH was said to be wrong by you and if I read it correctly chem geek said PH can be raised by adding baking soda. I also remember from college chemistry that any time you add anything with a different PH (it has been established that baking soda has a PH around 8 or so) the PH of the solution will be changed as well. As I told chem geek I hated chemistry and I retained very little from 20+ years ago but do remember some things. I will agree that PH rises from aeration but others things change it as well.

The only other thing I will say about what you wrote and others have said it before - it's long! Some people don't want to read info and anyone wanting a quick guide certainly won't read the info you posted. I once told somebody I know to get rid of the test strips he was using and get a drop kit - he couldn't handle putting 5 drops into the vials - besides newbies those are the type of people who probably run ito the problems that are causing them grief.

These are just my opinions.

[chem geek]

My comment about adding baking soda and raising PH was said to be wrong by you and if I read it correctly chem geek said PH can be raised by adding baking soda. I also remember from college chemistry that any time you add anything with a different PH (it has been established that baking soda has a PH around 8 or so) the PH of the solution will be changed as well. As I told chem geek I hated chemistry and I retained very little from 20+ years ago but do remember some things. I will agree that PH rises from aeration but others things change it as well.

Vinny,

Just to be clear, one does not normally use baking soda to raise the pH because baking soda mostly raises the TA.  So unless that is your intent -- to raise the TA -- you wouldn't normally use baking soda.  If you are using a net acidic source of chlorine, such as Dichlor, then the TA will be dropping over time so using baking soda will compensate for that and this was your example as you were increasing TA by 40 ppm or more.  One week of Dichlor at 2 teaspoons per day in 350 gallons would drop the TA by around 10 ppm when measured at the same pH (use of more Dichlor or of MPS would drop it more).  Normally, well-mixed baking soda carefully and slowly added to water with thorough mixing but minimal aeration won't raise the pH very much at all, but as you saw it did for you and this can happen if the water getting concentrated baking soda were to outgas right away which is certainly plausible (if you add baking soda to hot water you can see this carbonation effect at the surface).

If there were no outgassing effect, then adding enough baking soda to raise the TA from 80 ppm to 120 ppm would raise the pH from 7.5 to around 7.6.  Since you saw more of a rise, not all of the baking soda went into and stayed in the water.  Some of it quickly outgassed as carbon dioxide, probably near the surface as you were adding it since the TA would be very high locally until the water got more thoroughly mixed.  The problem is that having the pH rise in a consistent manner is tricky since it depends on how quickly you add it and how quickly it mixes and dilutes.  Also, if you don't want to raise the TA as much but want to raise the pH, then baking soda isn't a good choice -- pH Up (sodium carbonate) would be better and 20 Mule Team Borax or aeration would be even better.

For those interested in the chemistry, most of the effect of having the pH rise from adding baking soda is from the following:

NaHCO₃(s) ----> Na⁺ + HCO₃^-
Baking Soda ---> Sodium Ion + Bicarbonate Ion

HCO₃^- + H₂O <---> H₂CO₃ + OH^-
Bicarbonate Ion + Water <---> Carbonic Acid + Hydroxyl Ion
THIS IS WHAT MOSTLY CAUSES THE pH TO RISE

H₂CO₃ <---> CO₂(aq) + H₂O
Carbonic Acid <---> Aqueous Carbon Dioxide + Water

CO₂(aq) ---> CO₂(g)
Aqueous Carbon Dioxide ---> Carbon Dioxide Gas

It is that last step that is the outgassing of carbon dioxide and drives more of the second reaction to occur which is what causes the pH to rise more.  Were it not for that last step, the first steps would have the pH rise only a little since most of the added bicarbonate remains bicarbonate (at a pH of 7.5, 94.1% of the carbonates in the water are in the form of bicarbonate ion, 5.7% is in the form of aqueous carbon dioxide, 0.2% is in the form of carbonate ion, and a very small amount is in the form of carbonic acid).

Richard

[Flyonthewall]

are there any forms of granular chlorine, such as spa 56, that have less or no cya?  is it a hard fact that chlorine effectiveness goes down at the exact rate as cya increases.  in other words if cya at twice the recomended level decreases effectiveness by half is it accurate to say that it always decreases at the same rate as cya rises beyond these levels?

[chem geek]

are there any forms of granular chlorine, such as spa 56, that have less or no cya?  is it a hard fact that chlorine effectiveness goes down at the exact rate as cya increases.  in other words if cya at twice the recomended level decreases effectiveness by half is it accurate to say that it always decreases at the same rate as cya rises beyond these levels?

The amount of CYA in any Dichlor product is the same in proportion to the amount of chlorine that is added.  The CYA is not separate from the chlorine.  It is a combined chemical species (Dichlor is shown here; CYA is shown here).  When in water, some of the chlorine attached to the CYA becomes free hypochlorous acid.  The following are chemical facts independent of concentration or pool/spa size.

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

As for the disinfection rate vs. CYA level, I wrote about that here including links to various scientific studies showing the roughly proportional decline.  The proportionality comes from the chemistry so is not a surprise.  However, most bacteria are very easy to kill so even a lower disinfection rate is not normally a problem.  That's what Vermonter found and is why he proposed Dichlor-only after a soak as being OK.  I just noticed that there were quite a few problem reports with those who thought they had proper sanitation, but found issues after 1-2 months of Dichlor-only use in tubs that were used a lot (i.e. every day).  It's no doubt a small percentage of incidents and it's too small a number to be "proof" of anything, but I figured why not look at the science and come up with an alternative method for more consistent sanitation.

Richard

[tony]

are there any forms of granular chlorine, such as spa 56, that have less or no cya?

Lithium hypochlorite is a granular chlorine that has no CYA or calcium.  It does have a relatively low active chlorine percentage at 35 and is the most expensive practical chlorine.  With a pH of 11, it is very close to bleach.  At 65% other stuff, lithium adds significantly to TDS.

[Nitro]

I am not one to recommend bleach to anyone...

Just curious. Why would you not recommend it?

[tony]

Just curious. Why would you not recommend it?

First, I don't feel I am qualified in this field to recommend anything.  I can only comment on my experiences with the products I try or use.  I have found bleach to work wonderfully, but I feel individuals should be very comfortable with the chemistry before using it.  Owners look to their dealers and manufacturers for expert advise and bleach definitely goes against the grain.  IMO, if someone has used bromine or a more widely acceptabe form of chlorine for a while, has experienced the ups, downs, ins and outs of water issues and would like to experiment with something outside the box that may or may not be better than what they've been using...then bleach may just be the trick.  I use it and don't see any reason to change right now, but again, I can only comment on my experience.  If people want to use that in their decision to use or not use a product, then that is good, but it is not a recommendation.

[Rayman]

I guess I am one of few who use Trichlor tabs in a floater and dose with Dichlor after heavy use and use MPS to shock on weekends.  My water is always fresh, my cover is over 3 years old and looks great and I change my water every 4 months.

I love my water and it loves me.....Happy Tubbing

Ray

[Vanguard]

Okay, I think the horse is dead and it is being thoroughly beat.  Just my one cent.

[TubsAndCues]

Okay, I think the horse is dead and it is being thoroughly beat.  Just my one cent.

Horsey rides are only one penny!  I'm in!