Pool Water Chemistry

[Jonzjob]

[quote user="chem geek"] We're going to be in southern France on a barge trip in about a month as well as in Paris.  We love France.

Richard
[/quote]

If you are going to be in the Carcassonne area then PM me and we can possibly meet up as we live quite close. I will be able to pick your brians peut etra???

Our pool is also a vynl liner pool as are a heck of a lot of pols around us. It is a very popular type of pool...

[chem geek]

[quote user="Jonzjob"]If you are going to be in the Carcassonne area then PM me and we can possibly meet up as we live quite close. I will be able to pick your brians peut etra???

Our pool is also a vynl liner pool as are a heck of a lot of pols around us. It is a very popular type of pool...[/quote]

That's very generous of you.  The closest I will be is in Pézenas which is about 56 miles away.  I believe we get on the barge at Marseillan (after staying overnight at Montpellier) and after Pézenas head mostly east to Sète, Frontignan, Villeneuve-lès-Maguelone, Aigues-Mortes, Saint-Gilles, Pont du Gard, Avignon, Arles and Beaucaire.  I've been to Avignon before, but not any of the other places.

Regarding vinyl pools, they have the advantage of not having to worry so much about the water balance with respect to Calcium Hardness (CH) and they are less expensive, but are much more sensitive to chemical additions.  If Trichlor pucks/tabs are used in a floating feeder, you have to be careful that it doesn't park itself near an edge as the strong acidity can degrade the vinyl (you don't want to put such pucks in the skimmer either since the acidity can ruin heaters and pump seals if the pump isn't running all the time).  Even in my own plaster pool years ago a Trichlor feeder parked itself near some stainless steel bars in the pool and rusted the (lesser quality steel) mounts nearby.  There are special kinds of Trichlor pucks designed to be OK for use in a skimmer such as the Smart Sticks shown [url=http://www.parpools.com/page/poolcare/BioGuard_Smart_Sticks.html]here[/url].

When adding acid or chlorine to the pool, it is best to pour slowly (very slowly, in the case of acid) over a return flow in the deep end with the pump running.  For extra safety, lightly brush the side and bottom of the pool to ensure thorough mixing.  Liquid chlorine and acid are denser than water so adding too quickly can have them settle to the bottom which is a particular problem in pools without floor drains (e.g. above-ground pools) since the circulation is poor near the bottom.  Some people slowly pour chlorine into the skimmer; I'm not confident that this is OK.  For sure, one should never, ever pour acid into the skimmer -- not even slowly as it's WAY too acidic.

Very inexpensive above-ground vinyl pools, such as Intex pools in the U.S. (as shown [url=http://www.intexcorp.com/agp.html]here[/url]) have additional issues since the pump and filter supplied with the pool are woefully undersized and not of high quality (as the adage goes, you get what you pay for).  Such pools have a fairly low tolerance for changes to the water, so moderate bather loads can cloud them up (with lotions, etc.) and if they ever get algae it takes a very long time to clear.

If you find that your pH tends to rise rather quickly in your SWG pool and that you are frequently having to add acid, then you can follow some of the suggestions I gave earlier such as lowering the TA level and with a vinyl pool you can even go below 80 ppm though you should start there to see how things go.  If that isn't sufficient, you can consider the 50 ppm Borates.  On the other hand, if you are happy with your situation, follow the adage "if it ain't broke, don't fix it".

Richard

[Albert the InfoGipsy]

Give my regards to the harbour master at Marseillan. He (or one of his predecessors) allowed us to stay withour mooring charges when our propellor fell off in the middle of the harbour.

Try to sample some of the local booze.

[Théière]

So the story so far is, Americans drive great big gas guzzling cars, they are poluting the environment with more Co2. They eat huge portions of food usually high in sugars and salt. They export their rubbish food around the world making everyone fat.

The solution to almost all pool problems is dumping huge dosses of chlorine into their pools and running them at higher levels than required just incase they get a tiny bit ill occasionally.

Need I go on:

Then they start lecturing the rest of the world on what we are all doing wrong. Chem geek, why don't you visit your pool school and correct a few of the "FACTS" that they have wrong or are based on out dated information, Why because the products are not American?

Bacteria exists in pools because there is a redily available food source, restrict the food source and bacteria levels will fall.

Remove the sand and replace with zeolite,  AFM, or a good cartridge filter and filter out the food, then you can run on lower levels of chlorine saving a bit of the ozone layer for the rest of us.

Now that's my rant over.

I would like to say having studied a lot of your posts and links, It is always refreshing to update on current studies and knowledge so as to remove the old and sometimes very old beliefs. I was particularly interested in the ph bounce and TA/CH discussion, This merits more investigation any info you have would be good.

So far Chem Geek you have not mentioned alternative sanitisers i.e. permonosulphates etc, which do not suffer from u.v. degredation or evaporation in the same way as Chlorine and would have been a useful solutuion for the toddler pool scenario where the water depth is shallow and chlorine is used up very quickly. Spas can also benefit from non chlorine products as the fog layer is not as toxic to the user and chlorine is evaporated so quickly from spas.

Over to you.

Poppy, you should look for a phosphate lowering aditive, very high phosphates around rural France and that makes for good growth for the farmers and not so good for us pool owners.

[Poolguy]

Why Teapot Ol' chap

Good to have you in the frey, stout fella...!

Don't forget that Zeolite also removes ammonia from the water which is one of the principle culprits in Chloramine production (yucky chlorine smell) and other nasties.

Zeolite also goes some way to remove phosphates and nitrates but this is never a published claim as it doen't cover all variables.

I partuclarly like your reference to reducing chlorine levels the 'just enough', I've been banging on about this for ages and really not sure that anyone was listening.... (made my day that has..!)

Because with 1 micron filtration from a zeolite filter and a 3 hours circulation time (I notice that Chemgeek mentioned 5 hours and 1 water changer per day- I recommend 2 water changes per day, and so does DDASS who require it) there is bearly nothing in the water to sanitise, hence less demand for chlorine QED.

In Australia, we use an intergrated system to keep the water clean, not just to 'nuke it good jake', so I am tring to introduce that idea here - tough job.

Basically its what you don't put in the pool that counts not what you do. That means only Sodium hypochloride 9.6%(chlor), Sulphuric acid (pH-), Bicarbsoda (TA+) Isocyanuric Acid (stabliser)...... thats it!!!!!!  No flocculants, no antialgea (don't need any) no Choc, no sun absorbers, nothing else......and never, never, never, saturate potable drinkable water with sea salt........ water as pure as it can be!

Hey ho...

Andrew

[Théière]

Forum viewers,

If you use sand for filtering, you will almost certainly need antialgea, flocculent and choc, not to mention a bit more time, If you use a higher quality filter medium, you will be able to do without the aformentioned apart from maybe at start up and close for choc.

Occasionally because of the farmers using phosphate fertiliser, you may need to remove the phosphate, If you are building a new pool try and add another skimmer, a couple of extra returns and a floor drain to increase the water turnover.

There you go, TWO sentances and Four lines, QED.[:D]

[Poolguy]

Bravo......

 

Teapot your the greatest!

Andrew

[Poppy]

Thanks Teapot for the info re phosphates [:D]

[chem geek]

[quote user="teapot"]So the story so far is, Americans drive great big gas guzzling cars, they are poluting the environment with more Co2. They eat huge portions of food usually high in sugars and salt. They export their rubbish food around the world making everyone fat.

The solution to almost all pool problems is dumping huge dosses of chlorine into their pools and running them at higher levels than required just incase they get a tiny bit ill occasionally.

Need I go on:

Then they start lecturing the rest of the world on what we are all doing wrong. Chem geek, why don't you visit your pool school and correct a few of the "FACTS" that they have wrong or are based on out dated information, Why because the products are not American?

Bacteria exists in pools because there is a redily available food source, restrict the food source and bacteria levels will fall.

Remove the sand and replace with zeolite,  AFM, or a good cartridge filter and filter out the food, then you can run on lower levels of chlorine saving a bit of the ozone layer for the rest of us.

Now that's my rant over.

I would like to say having studied a lot of your posts and links, It is always refreshing to update on current studies and knowledge so as to remove the old and sometimes very old beliefs. I was particularly interested in the ph bounce and TA/CH discussion, This merits more investigation any info you have would be good.

So far Chem Geek you have not mentioned alternative sanitisers i.e. permonosulphates etc, which do not suffer from u.v. degredation or evaporation in the same way as Chlorine and would have been a useful solutuion for the toddler pool scenario where the water depth is shallow and chlorine is used up very quickly. Spas can also benefit from non chlorine products as the fog layer is not as toxic to the user and chlorine is evaporated so quickly from spas.

Over to you.[/quote]

I did not say that the 1.5 ppm FC with 30 ppm CYA from an automated dosing system that Poolguy recommends was a problem.  I said that in manually dosed pools a slightly higher chlorine level of 2.2 ppm FC would prevent algae growth in virtually all pools at that CYA level without the need for additional algaecides.  There is more than one way to control this and I gave examples of having even lower active chlorine levels such as 1-2 ppm FC with 100 ppm CYA (that's a factor of 3 lower in active chlorine level than what Poolguy recommends) by using alternatives to prevent algae growth including algaecide (PolyQuat 60) or a phosphate remover (to remove an essential algal nutrient).  It seems that you are connecting high FC with active chlorine when the two are not directly related without knowing the CYA level.  And if you have ever swam in an indoor pool that used chlorine, then you likely exposed yourself to far higher active levels of chlorine since CYA is not normally used in indoor pools.  I was proposing using a low level of CYA in indoor pools to lower the active chlorine level to make it more consistent AND safer.  In fact, having 4 ppm FC with 20 ppm CYA in an indoor pool has 5 times lower active chlorine than 1 ppm FC with no CYA and produces 5 times less nitrogen trichloride and has 5 times lower dichloramine concentration during the breakpoint reaction of ammonia by chlorine (no one knows the details about chlorine oxidation of urea yet).  It's a heck of a lot easier to get a 5x reduction this way than via greater air exchange or via filtration (which requires multiple turnovers of the water), but this is not being looked at by anyone -- not here in the U.S. nor anyone in Europe as far as I can tell.

As for filters removing food sources, even microfiltration down to 1 micron will not remove chemical nutrients from the water that bacteria need to grow; they only filter out physical particles and larger pathogens (like cysts), not molecules or bacteria or viruses.  Active filters (AFM, activated charcoal/carbon, etc.) can help since they remove SOME chemicals, but I haven't seen any studies that show that they keep bacteria levels low enough to use lower chlorine levels (if you have links to such studies, please post them and I'll change my thoughts on this -- the AFM website has documents like [url=http://www.drydenaqua.com/afm/dissemination/papers/swimming_pool_news/lifecycle/AFM%20swimming%20pool%20costs.pdf]this one[/url] that only refer to bacteria fouling of traditional sand filters).  Some of these filters are great for filtering out Crypto and other protozoan cysts that are chlorine-resistant and the active ones also filter out chloramines, but filtration takes time and it takes 4.6 turnovers of water (in the ideal case) to run 99% of the water through the filter -- it is not fast so even if it did capture bacteria (which it doesn't), it would not be faster than the 15-60 minutes it takes for them to double in population.  Bather load and organics getting dropped into a pool are continually occurring and while filtration can help, it does not stop bacterial growth.  I am not at all against such systems; I'm just saying that they do not substitute for a fast-acting sanitizer.

Nevertheless, the main problem with too low of an FC level is that the chlorine can run out locally because circulation is not perfect and chlorine demand from bather load can overwhelm the chlorine rapidly (ammonia combines with chlorine VERY quickly to form monochloramine).  So the higher CYA approach I mentioned above would be perfect for this situation by letting you have a lower active chlorine level while still having sufficient FC to not run out.  This is possible because of CYA's role as holding chlorine in reserve and releasing it to maintain a fairly constant active chlorine level.  It does somewhat slow down bacteria kill times, but that's generally only a concern for person-to-person transmission in commercial/public pools.  Again, you need to stop thinking that FC by itself is measuring what you think it is -- it is NOT measuring active chlorine levels.  Most of the chlorine in a pool with CYA is in the form of chlorine attached to CYA that is not very reactive -- it doesn't kill bacteria, doesn't oxidize organics, doesn't breakdown in sunlight, etc.  It is a holder or reservoir that can react with water to form more active chlorine as the active chlorine level gets used up.

I don't know what you mean by your reference to the ozone layer.  Only long lived chlorine chemicals such as CFCs last long enough to get into the high atmosphere.  Some chlorine in pools leaves the water as hypochlorous acid (and even less as chlorine gas), but either one gets broken down in sunlight and converted to chloride when reacting in the air near the surface.  Such chlorine never makes it anywhere near the upper levels of the atmosphere.  Saying something about an entire chemical class or element like chlorine isn't very helpful since chlorine in salt as sodium chloride is vastly different than chlorine in hypochlorous acid that is different then chlorine found in CFCs.  The fact that chlorine in pools is relatively fast reacting makes it safer with respect to the ozone layer.  It was the fact that CFCs were relatively non-reactive that made them dangerous as they would survive as air currents would sweep them up to the upper atmosphere where small quantities would then produce chlorine radicals in the strong UV in the upper atmosphere.  And here again, the proper use of CYA would help reduce a pool's chlorine contribution to the air since the outgassing of chlorine in pools without CYA occurs orders of magnitude faster since the hypochlorous acid concentration is so much higher.

As for the effect of higher Total Alkalinity (TA) and its increasing the rate of pH rise, I refer you to [url=http://www.poolhelp.com/JSPSI_V1N2_16-30_AcidColumn.pdf]this document[/url] that describes why the "slug" and "acid column" methods of lowering TA do not work or at least are no different than even distribution of the acid around the pool.  The article does not talk about aeration at lower pH, but the paper does describe Henry's Law and carbon dioxide outgassing and the reactions of the bicarbonate buffer system.  Another source is the Wojtowicz paper referred to [url=http://www.poolhelp.com/j_v1n3.aspx]here[/url].  In that paper (I have a book that collects all the Wojtowicz papers) Wojtowicz finds that the rate of carbon dioxide outgassing is proportional to the square of the carbonate alkalinity so it's not just linear (he posits that this is due to facilitated transport).  However, the basic principle is straightforward.  Higher TA means more bicarbonate in the water and due to chemical equilibriua at a fixed pH of pools it also means more dissolved carbon dioxide.  The amount of carbon dioxide in the pool is higher while that in air has not changed so the rate of outgassing increases.  Lowering the pH of the pool shifts more of the bicarbonate to dissolved carbon dioxide while aeration or disturbing the water surface increases the rate of outgassing by increasing the surface area of the air-water interface.  I don't know who originated the "aeration at low pH" method, but I first saw it on The Pool Forum website [url=http://www.poolforum.com/pf2/showthread.php?t=191]here[/url] and I don't know where Ben Powell (PoolDoc) got the method or if he figured it out for himself.  The method is further explained (non-technically) [url=http://www.poolforum.com/pf2/showthread.php?t=6746]here[/url].  The method makes sense, but the concept of lowering the TA to reduce the rate of pH rise was something I first put forth starting in [url=http://www.poolforum.com/pf2/showthread.php?t=5379]this long thread[/url] where experiments were done that showed that it was effective at helping lowering the rate of pH rise in SWG pools.  An extreme example of this in a non-SWG pool is described in [url=http://www.poolforum.com/pf2/showthread.php?t=7870]this thread[/url].

I'm not clear on the CH part of the discussion you are talking about.  Are you referring to the saturation index generally?  Or to why a higher CH and lower TA is better even if the saturation index is zero in both situations?

As for alternative sanitizers, the monopersulfates (MPS or KMPS as in potassium monopersulfate) are not fast-acting sanitizers, at least by themselves or at pool temperatures.  They are oxidizers so are good at getting rid of ammonia and urea before chlorine reacts with them, thus preventing the formation of chloramines.  They do not kill bacteria quickly -- one exception being their use at higher temperatures in a spa along with silver metal ions that help catalyze the reaction (it's still slower than chlorine, but not by that much).  If one wants to protect chlorine in a wading pool, then using high levels of CYA, such as 100 ppm, will be better for that even though the depth is shallow, though one should raise the FC level somewhat as well.  However, the specific scenario that was given had water exchange with the main pool so one couldn't really use a separate approach for the wading pool compared with the main pool.  Nevertheless, if the wading pool were separate, then using MPS would at least reduce the rate of loss of chlorine from the bather load so is certainly a way to have lower total chlorine capacity, but since it's capacity that is desired, the high CYA approach would work as well for that purpose (though would form chloramines if MPS were not used).

As for alternative sanitizers in general, as well as for spas, they vary in their effectiveness.  Metal ion systems, typically silver for killing bacteria and copper for killing algae, aren't great choices for pools and especially not plaster pools unless you are very careful in controlling the metal concentration and in keeping the pH lower.  Staining from the metal as well as the "blondes getting green hair" are real issues that CAN be managed, but you have to be careful.  They also do not kill bacteria as fast as chlorine and aren't that effective against viruses (more of an issue in commercial/public situations).  In a spa, the use of metal ions makes more sense since they are generally not plaster and the hot temperatures let you use relatively low levels that will not generally precipitate and they are used in conjunction with either chlorine or MPS.  On the other hand, the pH tends to rise in spas (due to the strong aeration and higher temperature for faster carbon dioxide outgassing) unless you use an acidic source of chlorine (remember that Dichlor is net acidic when accounting for chlorine consumption) or add acid regularly.  There are systems that combine metal ions with regular dosing of non-chlorine shock, MPS, and that are close to, but not quite, as sanitized as chlorine spas but as I said they are pretty darn close.  However, most spa users don't follow the instructions and instead add either chlorine or MPS AFTER their soak while to prevent transmission from person to person you really need the sanitizer to be in the water DURING the soak.  Again, the risk is small in a residential situation, but in a commercial/public situation you are essentially taking a bath with other people.  The biggest problem that I see in spas is that most people do not use enough oxidizer, whether it's MPS or chlorine.  A rough rule of thumb I've come up with looking at hundreds of posts on spa forums (as well as some literature) is that chlorine usage in a spa is around 7 ppm FC in 350 gallons per person-hour of soaking.  This can get tranlsated not only into chlorine amounts, but equivalent MPS amounts as well.  A typical dosage of 2 teaspoons of Dichlor in 350 gallons (4 ppm FC) would be good for around a half-hour of one person soaking and would be the same as around 3 fluid ounces of 6% bleach or 4 teaspoons of MPS.

I prefer not to recommend a single approach but rather to lay out the pros and cons of each method and let people decide for themselves.  There is a spectrum of risk and a residential situation is different than a commercial/public situation.  On one hot tub forum, there was a spate of hot tub itch/rash/lung incidents and I tried to figure out why.  It's still hard to tell, but almost all of the incidents were either no chlorine level for an extended period of time or were proper FC levels, but the CYA level was high due to continued use of Dichlor (the "Vermont" or "Northman" method) after 1-2 months.  At just 4 ppm FC per day as with the above example, this adds around 25 ppm CYA per week so after a month or so the chlorine effectiveness against the bacteria that causes hot tub itch becomes much lower (that bacteria is heartier and will form biofilms if not killed very quickly).  So I recommended that people use Dichlor for a week and then switch to bleach, but for some that led to rising pH issues that were not tolerable, though for others this was a fine approach and many reported that their water even after 3 months or more was clearer than they had ever seen it.  However, you are right that the chlorine fumes are definitely stronger in a spa and intolerable for some so alternative systems such as the metal ions plus MPS are a reasonable alternative IF dosed properly.  There were no incidents of hot tub itch/rash/lung with those who used the metal ion system so it's certainly the best way to go if you have any chance of not maintaining proper sanitizer levels -- it's like insurance.

Richard

[Poolguy]

Gauwd...

I'm getting really bored with this now ... and I'm being missquoted....

I said that in manually dosed pools a slightly higher chlorine level of 2.2 ppm FC would prevent algae growth in virtually all pools at that CYA level without the need for additional algaecides.  There is more than one way to control this and I gave examples of having even lower active chlorine levels such as 1-2 ppm FC with 100 ppm CYA (that's a factor of 3 lower in active chlorine level than what Poolguy recommends): (ed Chem geek)

If I recommed 1.5ppm FC and 30CYN please tell me how the above can be a 'factor 3 times lower'..

and please make it simmple I just no longer what to read 2500 (more) words to the get answer.

Richard Ol chap, I haven't read anything from you that gives me anything to debunk the approach I've adopted, which incidentally works fine on more than 45,000 domestic and comercial pools world wide. I had great hope that you might have something to offer me, but I can see that you do not understand what I am asking you (which is surprising as I thought it was very clear). You know a lot about chemistry but you have a bit to learn about filtration, and an a tremendous amount to learn about listening to other people. They are telling me that your efforts a not wholly appreciated - you are not being helpful.

I am sure you don't really care as you seem to be really enjoying yourself.. work away, then if that's how you get your jollies.

 

Ta ta

Andrew

[chem geek]

1.5 ppm FC with 100 ppm CYA results in an active chlorine concentration (hypochlorous acid) of 0.006 ppm while 1.5 ppm FC with 30 ppm CYA results in an active chlorine concentration of 0.020 ppm.  That's over a factor of 3 difference in active chlorine.  The difference is due to the difference in CYA concentrations.  The higher CYA level of 100 ppm has more chlorine bind to it than at 30 ppm CYA thereby leaving less chlorine in its active form.

Your answer is above, but you made more than one post so I am responding to some of what you said in the other posts and the post above below.

I don't know why you think I'm trying to debunk anything you have adopted in terms of approach except possibly your saying that 200 and 300 ppm TA is no problem.  It's not always a problem, but in your systems that automatically dose both chlorine and acid you should find that having the TA at 80 ppm uses significantly less acid over time (unless the pools are covered most of the time).  I would think that would save your customers money in the long run or at least less frequent replenishment of the acid.

By the way, my one turnover per day was assuming a normal non-active filter in a (typically low bather load) residential pool; for commercial/public pools the regulation is a minimum of 2 turnovers.  If you are using active microfiltration where you are depending on filtration to handle more than just water clarity but for chemical removal as well, then a shorter turnover time (unfortunately at higher cost due to faster flow rates) and multiple turnovers per day would make sense.  Context is important.

As for algaecide or phosphate removers that I mentioned, those were alternatives only if you were to use lower active chlorine levels.  I said before that these were not needed if you maintained sufficiently high FC relative to CYA to kill algae.  Again, I'm not recommending one way or the other -- it depends on what your goals are.  If you want the lowest active chlorine level, then you need enough chlorine to kill bacteria (which is relatively easy) but won't have enough to prevent algae growth so therefore would need a supplement.  Your 1.5 ppm FC at 30 ppm CYA is high enough to prevent algae in most cases (possibly not with extremely high phosphate/nitrate levels) so you have chosen the chlorine only approach using chlorinating liquid.  That is what is promoted on The Pool Forum and Trouble Free Pool, but I prefer to give people options.  If someone wants to use Trichlor in a feeder and doesn't dilute their water, then they can use an algaecide or a phosphate remover to prevent algae instead of diluting the water to lower the CYA -- it costs more, but it's up to them as it can be more convenient.  Your chlorine dosing system is great and I said so in earlier posts.

[Théière]

chem geek,

the AFM website has documents like this one that only refer to bacteria fouling of traditional sand filters  yes but they also have this one and probably more.

http://www.drydenaqua.com/afm/applications/afm_swimming/reports/chlorine_byproducts/chlorine%20by%20products.pdf

Now, in the true sense of fair play, you did get an appology from Poolguy re: You are right that I did take offense at your remark on questionable validity (and claims with no substantiation).  Thank you for apologizing.

I believe, you should extend the same courtesy back to Poolguy, (no one knows the details about chlorine oxidation of urea yet).  It's a heck of a lot easier to get a 5x reduction this way than via greater air exchange or via filtration (which requires multiple turnovers of the water), but this is not being looked at by anyone -- not here in the U.S. nor anyone in Europe as far as I can tell.

"No one knows" and "but this is not being looked at by anyone--not here in the U.S. nor anyone in Europe as far as I can tell." surely means "claims with no substantiation"

This is a discussion forum and I think it is your turn to appologise.

 

[The Ps]

Chem geek

Thank you for your posts.   I have enjoyed reading them and have found them most informative.   I appreciate that they have been difficult reading for some but that will always happen..........even in explaining the offside rule in football/soccer that can happen.

Enjoy your time in France.   Marseillan is a great place to start your journey.   The Tavern du Port is a good place to eat but avoid the rest as they are, in my opinion, over priced for average quality food aimed at tourists.   The only exception is in the centre of the village where you will find a good but basic restaurant called the Boulevard where the locals eat and Table d'Emilie which is something very special; probably the most expensive in the town but worth every Euro.   If you get time before leaving port visit the Noilly Prat distilery where you can get an interesting tour, sample the wares and buy a bottle to keep you going on your journey.

[Poolguy]

Richard (Mr Chemgeek)

I do understand your construction but hear this if you can.

We live in France ...... you live in the US. These places are not the same and things are not done the same.

In this country Pools which are not for private use (that means more than one family) are controlled by the DDASS (Directione Department des Affaires Sanitaires et Sante - or Dept of Health), All pool operated in this fashion are controlled by means of regular testing of their water.

Their norms states:

Stabilisabte . Acid isocyanurique / MAXIMUM 75mg/l à maintenir de préférence entre 30 et 50mg/l

Do you notice a similarity with my advise .... perhaps? (if you can read French then I could give you a link)

Now you will say, that private pools aren't public and so you can do what you want and so , and so , blah blah blah

But now I say, and hear this ... concentrate now!

This is a public forum, and from my 4 years of contributing, mostly half or more of the contributors are operating Gites (holiday homes) with a pool, which is classed as 'public pools' and therefore controlled by the DDASS. Now if a pool owner either by following your advice, or going it alone or is even just not paying attention and Exceeds 75ppm CYN then the inspector is entitled to order that the pool be emptied/closed. That can be catastrophic for a small business.

You might find this unjust, not scientific, unnecessary, well its the law and if we want to live in France and conduct business then WE must abide by it.

Hence, when I give advice here, its this norm which constitutes the bulk of it, at least the guiding principle, so that the ALL people reading don't see one set of rules for a group and another for the rest..... that is a state of confusion.  A condition which I am sad to say, you have done a lot in the last 3 days to foster, with better than 10,000 words on the subject with recommendations which do not apply to us here. I said in the beginning that your advice was of ‘questionable validity’ (to which you took offence because you do not understand the above - the US is not the whole world and never will be), I apologised for offending you because I thought your motives were well meaning - to be helpful. Now, I think that you are being destructive and I ask you to consider this carefully.

Teapot (bless im) has followed the fray and thinks that there is a medium point, which I hope that we can find.

I know that your (perhaps sole) purpose to come on this forum is to give me a slap, you opened your remark by say as much.

Now you are slapped my friend.

Andrew

 

[Cat]

Both poolguy and chem geek are posting lloads of information that forum users may find very useful (even if a lot of it goes straight over my head, and how). 

Even if the advice is sometimes contradictory, I'm sure the differences can be settled without resorting to muskets at dawn. Can you guys agree to differ, amicably, pretty please?

[chem geek]

[quote user="teapot"]

chem geek,

the AFM website has documents like this one that only refer to bacteria fouling of traditional sand filters  yes but they also have this one and probably more.

http://www.drydenaqua.com/afm/applications/afm_swimming/reports/chlorine_byproducts/chlorine%20by%20products.pdf

Now, in the true sense of fair play, you did get an appology from Poolguy re: You are right that I did take offense at your remark on questionable validity (and claims with no substantiation).  Thank you for apologizing.

I believe, you should extend the same courtesy back to Poolguy, (no one knows the details about chlorine oxidation of urea yet).  It's a heck of a lot easier to get a 5x reduction this way than via greater air exchange or via filtration (which requires multiple turnovers of the water), but this is not being looked at by anyone -- not here in the U.S. nor anyone in Europe as far as I can tell.

"No one knows" and "but this is not being looked at by anyone--not here in the U.S. nor anyone in Europe as far as I can tell." surely means "claims with no substantiation"

This is a discussion forum and I think it is your turn to appologise.

 [/quote]

You are right.  I gave links and references and (too much) technical detail to much of what I posted, but with regard to the statement you quoted I did not.  I am sorry about that and sorry to be sensitive to Poolguy's remark.  I've tried not to get into any personal attacks, but it doesn't feel to me like there's a balanced level of civility (though some members are clearly very kind).  The latest and best breakpoint chlorination model (Jafvert & Valentine) has to be paid for (which I did) so I could not post a reference to it, but I do have a spreadsheet with that model (and others) that shows the result I referred to.  Also, it is well known in the water treatment industry that it is better to chlorinate water at a lower level of chorine for a longer period of time (for the same CT product) in order to reduce the amount of disinfection by-products that would otherwise be produced.  As to why this isn't looked at regarding indoor pools, I just think that the stabilized chlorine industry has been good at obscuring the chlorine/CYA relationship as in the U.S. they fund APSP TECH training and influence NSPF CPO training.  I don't know the situation in Europe.

The link you gave just says essentially the same thing (in more detail) regarding bacterial fouling in filters.  The reduction in bacteria they are referring to is in bacteria that grows in the filter medium in biofilms that are more resistent to chlorine.  This has nothing to do with controlling bacteria in the bulk pool water or preventing biofilms on pool surfaces and that's what I was referring to.  You still need chlorine in the bulk pool water for that purpose.  I would still like to see independent studies done to support these claims as some manufacturers make dubious claims.  If chlorine levels are maintained sufficiently and if there is proper circulation through the filter, then bacteria will get killed (very quickly) before being able to form biofilms in the first place.  I'm not saying that a problem can't get started if chorine levels got low, but that it might be able to be prevented.  Perhaps it's a unique problem with sand filters.  As Poolguy points out, I do not know filters as well as I know pool water chemistry.  In any event, having a filter media that inhibits bacteria growth certainly could not hurt.

Richard

[chem geek]

Andrew,

Thank you for explaining the differences in France vs. the U.S. as that does explain a lot of the misunderstanding in terms of why you would find some of what I say not applicable and why I would wonder why you are doing things a certain way -- though I really wasn't disagreeing with very much.

I didn't come to this forum to slap you.  I didn't even refer (link) to any posts directly in my first post (I didn't even pay attention to who posted the info I initially read until you responded to my post).  I just saw some information that was incorrect and most other information that was very good and wanted to both correct and add to the information.  Where I royally screwed up was in posting a very technical post rather than just starting out with an introduction and some questions.  I'm sorry I did that and am sorry I made you feel like I was slapping you.  It was certainly no way to start out a conversation.  If I just met someone for the first time and talked the way I wrote, they'd certainly walk away -- I forgot that a forum is like that.

I did not understand that many of your low-bather-load pools would come under commercial/public guidelines as holiday homes.  The fact that they must then operate under guidelines requiring 2 turnovers, etc. makes sense to me now, though I think it's an inappropriate use of applying one standard for high-bather-load pools to a situation where it is not needed.  It's not bad, however.  For whatever reason, one turnover even for sand filters in the U.S. works for most residential pools, but we don't have 3-hour turnovers either so normally pumps are run for at least 6 hours.  Perhaps the average residential pool size is bigger -- most are 7500 to 20,000 gallons (28,000 to 76,000 liters) -- or the pumps are smaller.

The CYA guideline of a maximum of 75 ppm with a preferred range of 30 to 50 ppm is very reasonable, especially for France where even southern France isn't at a latitude where the chlorine loss due to sunlight would be high enough to (normally) justify a high CYA.  So I now see that you couldn't operate at 100 ppm CYA by regulation, though you could at 75 ppm.  I was mostly giving that as an example of the principle, not saying you or anyone should do it.  In the southern U.S., however, such as in Arizona, parts of Texas, Florida, etc. the sun shines so intensely overhead that chlorine loss from sunlight is the biggest loss by far -- way, way more than that from bather load in residential pools (in commercial/public pools with high-bather load, it's still the bather load which dominates, so anything above around 30 ppm CYA isn't that helpful -- but they don't generally use active filters as you do).  It turns out that the traditional graphs of chlorine loss at varying CYA levels aren't right and that there is a non-linear beneficial effect at higher CYA levels.  So in the southern climates, running a pool at higher CYA levels even with proportionately higher FC levels (i.e. at the same active chlorine level) uses a LOT less chlorine (saves 50% or more FC usage per day).  In the U.S., the rules are by state, not national, but are essentially the same in every state at 1-4 ppm FC limits and 100 ppm CYA maximum.

Again, I'm sorry I offended you.

Richard

[Jonzjob]

Can one of you guys explain, in single sylable words preferably, what the difference is between an active and a passive filter please???[8-)]

[chem geek]

Activated Filter Media (AFM) removes certain chemicals via some form of attraction (chemical "stickiness") or destruction (chemical "conversion") in addition to physical removal of particles down to a certain size.  Passive media (i.e. regular cartridge, sand, DE filters) only does physical removal of particles down to a certain size.  I'm not clear on whether filters that only inhibited bacterial growth in the filter itself (in addition to doing physical filtering) would be called active, but I suspect that they might (to me, they are just "enhanced" to prevent bacterial fouling).

If you have a drinking water filter at home, that is most likely an active filter as it removes chemicals such as chloramines and heavy metals (and probably chlorine as well).  The AFM filters from Dryden Aqua described [url=http://www.drydenaqua.com/afm/]here[/url] and the ZEL-ALU on the Poolguy website [url=http://www.poolguy.fr/products/product-filtration.htm]here[/url] are active and they vary in which chemicals they remove.

There's more I can say about ZEL-ALU removing ammonia and whether that's useful or not and there's more about the bacterial fouling and "biofilm" in the filter issue as I had an E-mail conversation with someone from Dryden-Aqua back in July of this year.

(John "The P's": thanks for the restaurant tip.  Albert: will do re the harbour master at Marseillan.)