Moving the local technique

[Vanman]

We had a (50 sq meter) pool installed a couple of years ago by a local firm, and it has been extremely good - no problems at all.

But it isn't heated - and the local technique is one of those buried ones. It's difficult to get at the pump and multiway valve (the lid doesn't open very far, and you have to stretch to get at the controls), and we don't like the way the box sits in the middle of the grass.

We've thought about putting up a structure like a garden shed at the bottom of the garden, with solar panels on the top, and with the pool machinery inside and a new heat-exchanger to heat the pool a little in late spring and early autumn. In summer the solar panels should heat our domestic water. The new site would also be about a meter lower down than the present one.

Here's the question. At present the machinery is about 5 meters from the pool. If we do this, it will be 15 meters further off - twenty meters from the pool. Is that too far?

I do understand that we might need a more powerful pump. But is there some other reason why the whole idea might not be practical? I'd really appreciate comments.

[Poolguy]

Well no real reason other than it will decrease your filtration rate and I would guess that it might already be fairly feable.

You should have 3 hours to circulate all of your water? So if you have a 10 x 5 pool @ 75m3 then you will need a 25m3/hr pump or some like a 1.5 - 2cv and filter to match.

If your moving it all then you should take advantage and change the sand to Zeolite as the measures you are taking to heat the pool will increace the tendancy for microbiological activity, so you should take extra precautions in Filtration and sanitisation to compensate.

I presume that you will be using evacuated tube panels to heat the pool and so the pressure circuit needs to be short as possible, like wise the circuit of pool water but you do not have that luxuary, you are adding 10 meter whihc means that there will be 20 meters of ground to heat up before the pool gets a look in. So Bury the pipes at least 60cm but more if you can and insulate them very well with foam or some form of non crushable insulation. You will need to insulate the pool as 80% of the heat in the water will be lost from the surface to the night sky. (bubbly style covers are NOT sufficient, you will need a thick foam or PVC floating cover or both at the least.)

There are many more suggestion I can offer but you'll have to send me your details by PM so that I can see what it is you are going to do.

Andrew

 

 

[Vanman]

Thanks Andrew that's helpful.

To summarise: there'll be more heat loss (unless someone invents a miracle insulation that cuts out all heat loss) and the extra friction from the longer pipes will probably mean I need a bigger pump.

As I said, the last few years the system has worked perfectly, nice clean water all the time even when the pool briefly got to 30 degrees with just sunshine, and I don't want to spoil that.

We probably would wish to change the sand (for new sand) when we move the machinery. I see you suggest Zeolite. I'd wondered about crushed glass as being a slightly more ecological alternative than Zeolite with a similar filtration ability (2 - 3 microns). I'd like to think all the bottles I send to the bottle bank find a good home. But are there drawbacks to glass?

Thanks again

[Théière]

Hi Vanman,

When you say glass there are distinctions.

Ordinary crushed glass, absolutely useless and dangerous, just a way of getting people to buy old rubbish at a premium price. 

AFM (advanced filter medium) made by Dryden, a treated glass with really good properties to prevent the growth of bacterial film in the filter.

Regarding your pump, you should also PM Andrew with the details of your pool, re: the number of skimmers, returns and floor drain as upgrading your pump could cause a much higher pressure throught the system and that can have a very detrimental effect.

EDIT: what size are the plumbing pipes 50mm? consider using 63mm for the extenstion that will help take the strain off the pump and filter.

[Vanman]

Thanks for the clarification, teapot.

What I wanted to know when I first asked (and what I do know now) is whether there was any major problem in shifting the local technique that distance - the kind of problem that would make it impossible. That's because I need to get planning consent *first* for the abri with the solar panels - and then pour a slab of concrete for the foundations. That's about as far as my DIY skills are going to go - I will be getting in a professional to do the replumbing.

I'll probably hire a digger and dig the trenches myself: there's a second trench to go from the panels to the house. The controls for the solar heating will be more complex than I can manage myself.

I didn't want to waste to much time on a project that might have proved to be impossible. I'm most grateful for the responses. Still don't know really what to do about a new/different filter medium though! The pool is a salt/chlorine generator one (and, as I've said, so far it has worked very well). But the works won't start until later in the year, so I've some time to make up my mind.

[Poolguy]

If you email me your email address then I'll send you a Technical comparison between AFM and Zeolite.

For the record, AFM is not more ecological its much, much less, as there is significant energy consumed in manufactuing AFM and Zeolite is a natually occuring mineral which is simply crushed. They two are not the same in any way, as one of the unique properties of Zeolite that of absorbtion of ammonia and therefore inhibition of chloromines is not at all enjoyed by AFM - so for the price and the performance, its ZEL EAU all the way.

If you want an integrated solution for the whole Local technique and solar system then PM me as we are speciailists for that.

 

Good luck

Andrew

 

[chem geek]

Chlorine (hypochlorous acid) combines with ammonia VERY quickly to form monochoramine.  In a pool where the Free Chlorine (FC) is around 10% of the Cyanuric Acid (CYA) level, so is roughly equivalent to a pool with 0.1 ppm FC and no CYA, half of any introduced ammonia combines with chlorine in 12 seconds, 90% of it combines with chlorine in 40 seconds, and within a minute the formed monochloramine begins to break down with additional chlorine via breakpoint chlorination that takes hours to complete.  So long as you have sufficient chlorine in the water, you won't see any ammonia and it certainly won't circulate quickly enough to get to the filter.  So unless the Zeolite absorbs monochloramine, the fact that it absorbs ammonia is a moot point.

You can easily prove this for yourself by adding a small amount of ammonia to an excess of chlorine (all diluted in water) and measure the Free Chlorine (FC), Combined Chlorine (CC) and ammonia content.  You will find that the FC drops (but is still present) to form Combined Chlorine (CC) and that after a minute there is no measured ammonia so long as there was sufficient excess of FC to ammonia.  If the water doesn't have any CYA in it, then the CC will break down more quickly so you need to simulate real-world pool conditions and could use a bucket of pool water as a starting point, increasing the FC and adding a very small amount of ammonia (one drop of a 10% household ammonia solution in 8 liters is about 0.6 ppm ammonia and one should have an FC of over 6 ppm to have excess FC; one drop of 6% bleach in 8 liters is about 0.4 ppm FC so add at least 1 ml of bleach first, before the ammonia, if the FC isn't high enough to start with).

Having a non-chlorine shock (e.g. potassium monopersulfate, MPS) in the water can oxidize the ammonia faster than chlorine can combine with it to form monochloramine, but any filtration method removing ammonia (and not monochloramine) is pointless unless there is so little chlorine in the water that it runs out and excess ammonia is able to be present.  Even then, the filter would have to bind to the ammonia so strongly as to prevent it from reacting with any chlorine that was subsequently added and circulated through the filter.

Urine and sweat are mostly composed of urea and much less as ammonia.  In terms of nitrogen content, sweat is 68% urea and 18% ammonia, urine is 84% urea and 5% ammonia.  A chemical model for oxidation of urea by chlorine has not been validated, but most proposals talk about a slow (hours to days) combining of chlorine with urea followed by a more rapid breakdown of a chlorourea to dichloramine and trichloramine.  So any filter medium that absorbed enough to inactivate (or to oxidize) urea as well as monochloramine would be beneficial.  Urea and monochloramine are both uncharged so it's unclear that Zeolite would filter these out.

Richard

[Poolguy]

Nonsence

[Jonzjob]

[:D][:D][:D]

Still along the lines of the water chemistry.

Did you get any gen on the seperate tabs for the Scuba+ yet Andrew? Not the full kit, just the seperate test tabs?

[chem geek]

What about your sources for your assertion of "Nonsence"?  What source do you have that shows that ammonia and chlorine do not combine to form monochloramine much faster than would reach the filter?  See [url=http://cat.inist.fr/?aModele=afficheN&cpsidt=15526929]this link[/url] for one of many sources for the rate constant of 3.07E+06 for hypochlorous acid combining with ammonia.  The Wei & Morris model used a rate constant of 6.13E+06 as did Selleck & Saunier.  The latest full breakpoint chlorination model is from Jafvert & Valentine (1992) that gives 4.17E+06 and you can purchase the paper describing this model [url=http://pubs.acs.org/doi/abs/10.1021/es00027a022]here[/url].

0.1 ppm FC equivalent with no CYA (using a larger FC would just make the reaction even faster) is the following (all chlorine "ppm" is relative to chlorine gas)

(0.1 mg/L) / (1000 mg/g) / (70.9064 g/mole) = 1.4E-06 moles/liter

at a pH near 7.5, half of this is hypochlorous acid, so 7.0E-07 moles/liter

So the rate of the reaction of chlorine combining with ammonia to form monochloramine is

Rate = Rate Constant * [HOCl] * [NH3] = 3.07E+06 * 7.0E-07  * [Ammonia]  = 2.1 * [Ammonia]

and this result is in moles/liter/second

From the above it is seen that ammonia itself combines with hypochlorous acid in under a second (since the net rate factor of 2.1 is >1), but we now need to see how much ammonia there is at a pH of 7.5 since most of it will be ammonium ion and as the ammonia is depleted, ammonium ion will rapidly convert to ammonia so the reaction will continue (with exponential decay).

0.1 ppm total ammonia is the following (all ammonia "ppm" is relative to atomic nitrogen)

(0.1 mg/L) / (1000 mg/g) / (14.0067 g/mole) = 7.1E-06 moles/liter

There are many sources for the Ka or Kb of ammonia/ammonium, but [url=http://www.coolschool.ca/lor/CH12/unit4/U04L13.htm]this link[/url] is a pretty clear one.  I'll use the Ka constant of 5.6E-10.

[H+] * [NH3] / [NH4+] = 5.6E-10

at a pH of 7.5, [NH3] / [NH4+] = 5.6E-10 / 10^(-7.5) = 1.8E-02

so it is clear that most of the total ammonia is in the form of ammonium ion, NH4+.

Total Ammonia = [NH3] + [NH4+] = [NH3] + ([NH3] / 1.8E-02) so

[NH3] = Total Ammonia / (1 + 1/1.8E-02) = 7.1E-06 / 56.55 = 1.3E-07

so the rate is 2.1 * 1.3E-07 = 2.6E-07 moles/liter/second

If I ignore the slowdown as the ammonium ion level drops, I get 7.1E-06 / 2.6E-07 = 27 seconds.  The numbers I computed and referred to in my earlier post used the accurate exponential decay formulas.

[EDIT]

(NOTE: I redid this to use a simpler explanation)

The equilibrium constant for the reaction of chlorine with ammonia to make monochloramine is 2.0E+11 (ratio of 4.17E+06 / 2.11E-05 rate constants from Jafvert & Valentine cited above).  In case one thinks that there will be a lot of ammonia left for the filter to remove at equilibrium, the amount would be:

[NH3] = [NH2Cl] / [HOCl] / K = 7.1E-06 / 7.0E-07 / 2.0E+11 = 5.1E-11

[NH4+] = [H+] * [NH3] / 5.6E-10 = 10^(-7.5) * 5.1E-11 / 5.6E-10 = 2.9E-09

this is 2.9E-09 / 7.1E-06 = 0.04% of the total initial ammonia or resulting monochloramine amount.  Even if it were completely removed during each pass of water through the filter, it would take thousands of turnovers to remove the monochloramine via ammonium ion adsorption.  However, the removal will have more ammonia replenished from monochloramine so we need to look at that rate.

The reaction rate of replenishing ammonia that is removed has a rate constant of 2.11E-05 so the rate is:

k * [NH2Cl] = 2.11E-05 * [NH2Cl]

so the half-life of monochloramine assuming complete and instantaneous removal of ammonia via ammonium ion is t = -ln(0.5)/2.11E-05 = 32851 seconds or 9.1 hours.  This assumes the entire body of pool water is simultaneously exposed to the zeolite, but of course that's not what happens.  Even if the water is in the filter for 2 minutes and the turnover time is 3 hours, that's around 1% of the water in the filter at any point in time so the half-life is around 900 hours.  Unless the zeolite removed monochloramine directly, it isn't effective at removing chloramine.

The bottom line is that the process of zeolite removing ammonium ion from the water would result in a negligible reduction in monochloramine and that it wouldn't prevent it's rapid formation so long as there was chlorine in the water.

[END-EDIT]

The source for the composition of sweat and urine is Table 4.1 in [url=http://www.who.int/entity/water_sanitation_health/bathing/srwe2full.pdf]this document[/url].

The source for the chlorine/CYA relationship defined in a paper published in 1974 is [url=http://richardfalk.home.comcast.net/~richardfalk/pool/OBrien.htm]here[/url].

Your sources?

[chem geek]

Instead of the formal chemical derivation, perhaps you'd prefer something in words from a book to make it more clear such as in [url=http://books.google.com/books?id=nBCqLMCk6ooC&pg=PA13&lpg=PA13]this link[/url] which says the following:

The formation of monochloramine is dependent upon the ratio of chlorine to ammonia-nitrogen (Cl2:NH3-N), pH and temperature.  Monochloramine is the predominant chloramine species at 25ºC when pH values are greater than 5.5 (Figure 1.3).  Under optimum pH conditions (pH 6.5-9.0) monochloramine formation (Equation 1-7) is completed within seconds or less at a 5:1 Cl2:NH3-N weight ratio and 25ºC.

:

For example, the formation rate of monochloramine at pH 7 and 25ºC is 0.2 seconds for 99 percent conversion...

:

Dichloramine will form in the pH range of 7 to 8 according to Equation 1-8 if the chlorine to ammonia-nitrogen weight ratio is 10:1, however the reaction is slow.  Accordingly, the proportion of monochloramine in the pH range of 7 to 8 is much higher than dichloramine.

The very fast 0.2 seconds for 99 percent conversion is at the lower pH

of 7.0 compared to 7.5 and also at higher chlorine concentration (i.e.

no CYA present and higher Free Chlorine concentration).  [url=http://monokloramin.kayabek.net/chloramine/ChloramineUpdateTraining.pdf]This link[/url] also refers to the 0.2 seconds, but again this is more for water treatment so no CYA and higher chlorine concentration.

In the same book [url=http://books.google.com/books?id=nBCqLMCk6ooC&pg=PA64&lpg=PA64]here[/url] they say:

Assuming complete mixing, at neutral pHs of 7 to 9 and temperatures of 20ºC to 25ºC, the reaction of ammonia and chlorine to form monochloramine takes from 0.07 to about 3 seconds, which almost immediately eliminates the free chlorine and reduces DPB formation potential.

The above is in water treatment where there is no CYA and in this case they are not adding extra chlorine much beyond the ammonia demand.

In [url=http://dnr.wi.gov/org/es/science/lc/OUTREACH/-Training/chlorine/Breakpoint_Cl2.pdf]this link[/url] there is a table on a slide entitled "How fast is chloramine formation?" where at pH 7 the time for 99% conversion of free chlorine to monochloramine at 25C is 0.2 seconds.  They list the molar quantities of hypochlorous acid (HOCl) as 0.2xE-03 and NH3 as 1.0E-03.  These are higher than the pool example I gave which explains the faster 0.2 seconds result.  In fact, it appears that they have the amounts reversed since I get the 0.2 second result if I use a total chlorine of 1.0E-03 and total ammonia of 2.0E-04 (0.2E-03) and it makes no sense for them to have less chlorine than ammonia (on a molar basis) or else one would never achieve 99% completion.

Interestingly, I ran into [url=http://www.ukdiscus.co.uk/library/general-articles/chloramines.html]this link[/url] that talks about using a "duo pod" or two filter approach to removing monochloramine for aquariums.  The first filter has activated carbon which converts monochloramine to ammonia.  The second filter uses zeolite to filter out the ammonia created from the first filter.  Now that makes sense and would be a decent system for removing monochloramine from water, but unfortunately would not be useful for pools since the activated carbon would remove chlorine as well.  [url=http://books.google.com/books?id=nBCqLMCk6ooC&pg=PA26&lpg=PA26]This link[/url] to the same book referenced earlier in this post describes this in more technical detail, but note that zeolite removes ammonia, not monochloramine (at least not enough to be efficiently used by itself), and that an activated carbon is used before the zeolite to convert monochloramine to ammonia.

Again, your sources?

[chem geek]

Since there's been no reply to this, I've been looking for the sources of the claim that Zeolite prevents chloramine formation by adsorbing ammonia.  All I can find is claims from the Zeolite manufacturers including: [url=http://www.northernfiltermedia.com/zeobest_info.htm]Zeobest[/url], [url=http://www.zeoinc.com/zeosand.html]ZeoSand[/url], [url=http://www.zeobrite.com/Consumer.asp]Zeobrite[/url], [url=http://www.zelbrite.com/product.html]Zelbrite[/url] and, of course, [url=http://piscinekitdirect.com/catalog/product_info.php?products_id=484]Zel - Eau[/url].  I could not find any scientific papers or independent studies showing that ammonia in chlorinated pools was able to be filtered out by Zeolite before such ammonia combined with chlorine to form monochloramine.

I believe what has happened is that someone used two true facts to draw an incorrect conclusion as follows:

TRUE: Zeolite removes ammonia (via ammonium ion) from water that is filtered

TRUE: Chlorine (hypochlorous acid) combines with ammonia to form monochloramine

FALSE: Therefore, Zeolite prevents or reduces chloramine formation in pools

The reason that the conclusion is false is that it requires the ammonia to persist in the presence of chlorine long enough to be able to be filtered out by the Zeolite and that simply doesn't happen.  I'm guessing that one manufacturer posted the claim and then everyone else followed suit, just assuming it was correct.

There is a task force on Zeolites as part of [url=http://www.nsf.org/]NSF International[/url] so I've contacted them to see if I can get more info on where this claim came from.  I've also contacted the manufacturers noted above (except for Zel - Eau -- PoolGuy can ask his manufacturing source of zeolite for info supporting the "prevents chloramine formation" claim).

Richard

P.S. for some reason if one puts Zel - Eau in a post without the spaces, one gets Zel-Eau instead.  Does anyone know why that happens?

[Théière]

What I belive is that zel- eau (zeolite) is a much better filter medium than the sand that most of us are using today.  If your sand has been in use for more than 3 or 4 years it needs changing as it will contain a large amount of biofilm (bacterial build up) This bacteria will occasionaly break free from the filter a re enter the pool.  This can be why problems sudenly occur even though you have been trouble free for a couple of years. In commercial pools out breaks of legionare's desease have happended through just this type of situation.

If you cannot afford to change to AFM or zeolite, then at the very least change the sand.

 

 

 

You are absolutely right Chem geek zel- eau does automatically change to Zeolite, recon that's why Poolguy calls his product by the name he does [Www]

 

[chem geek]

Thanks.  I didn't mean to imply that Zeolite wasn't good.  It filters far better than sand or cartridge and is more comparable to DE or AFM in the resulting water clarity and "polished" look to the water.  I'm only focusing above specifically on the one claim that it prevents chloramine formation.  I'm not disputing the better filtration capability nor its ease-of-use, etc.

[Poolguy]

OK Mr Geek

I've been busy with the season opening, too busy to do the research necessary to support my assertions contra your tomb on Chloramines formation arising from Ammonia in the Water. But now to Summarise:

I contend that Zeolite will scrub ammonia from the water and so provide a benefit of less Chloramines formation – a worthy goal for any pool owner, private or commercial.

You dispute that in your lengthy work where copious book study citations provide substance to the chemical reactions involved.

My response is from empirical study.

I mean that I have been out testing pools for ammonia using the Palintest indophenol method and if it (ammonia) were present in a chlorinated pool for example I would contend that your theory is debunked as, according to you, it should have combined ... in 2 seconds I think you said, and therefore no been detected through this method.

Well the news is that I found Ammonia in EVERY POOL THAT I TESTED, even those that had Zeolite and in UV treated pools and so on.

So yes it is an issue to be considered and YES I can confidently say (I am satisfied at least) that ZEOLITE DOES REDUCE AMMONIA in chlorinated pools.

Because in all the pool I tested that had Zeolite in their filter for a significant time the Ammonia levels were insignificant <0,35mlg/lt

There were pools in the sample with sand that went as high as >5,5mlg/lt, and I think that we all agree that is getting serious;

Here is the table of results

Domestic pools				Commercial pools
Owner	Sand	ZELEAU	Comments	Location	Sand	ZELEAU	comments
John 11		0,25	In balance	Le Brande17	0,45		in balance
Andy  66		5,65	green, no chlor	Font Municip 85	0,04		Low chlor
Muriell  17		0,21	green,CYN too high	Bohat Child 56	0,07		fresh water
Steve 85		0,33	In balance	Bohat Slide 56	1,29		Green
Richard 85	4,56		Clear, indoor	Bohat Covered 56	5,65		Green
Dubois 17		0,29	Clear,
Rod 17		0,13	Clear Resin
James11	3,6		Green Oxymatic

 

 

This is not a large sample of pools and so scientific conclusion are not to be drawn till more testing is undertaken, but the trend is clear and further some of the pools in the study were tested with sand filtration and have now changed to Zeolite and so we shall benefit from a comparison before/after.

 

So to answer your question, my sources are

1. the pools I service, and

2. Palintest testing equipment and technical advise from their chemists.

 

I am sure that you will have something (or a great deal) to say about this but for the moment I stand by my comments earlier and go further to say that its clear to me that the claims made by the manufactures of Zeolite and the vast body of Doctorial research holds up to practical examination in the field.

 

In short…… IT WORKS, and Chloramines are reduced, because of less ammonia in Pool water ONLY if you use Zeolite to filter the water.  QED

 

Andrew

[Théière]

Blimey Andrew, your turning into PoolGeek [:D]

The reason why Zeolites can filter out Ammonia is due to the ion exchange that takes place inside the filter, bearing in mind that water companies add somwhere in the region of 0.5mg/litre to the supply water it's not surprising its found in the pools. The majority of ammonia comes from the bacteria that convert Urea that comes from humans.

Chloramines are also reduced if you use AFM from Dydenaqua.

[Jonzjob]

Hotly followed by a Teageekpot me thinks?[:-))]

That's why I don't drink the water! I've seen just what fish do in it, they don't get out when they want a wee you know!

[chem geek]

Andrew,

The indophenol method is described [url=http://www.hach.com/fmmimghach?/CODE%3AMETHOD10200_40006110%7C1]here[/url] where the test for ammonia actually creates monochloramine so one must first measure the monochloramine amount before going further with the test to measure ammonia.  Otherwise, you just end up measuring the sum of monochloramine and ammonia -- not ammonia alone.  This is also described [url=http://www.chemetrics.com/analytes/ammonia.html]here[/url] (the second test -- salicylate method -- salicylate is a phenol; these tests are also described [url=http://www.hach.com/fmmimghach?/CODE%3AEX_NITROGENAMM1436%7C1]here[/url]).  In other words, you have to subtract the monochloramine amount from the ammonia amount (in similar units) or re-zero the measuring device in two steps as described in the Hach instructions.  The Palintest description [url=http://www.palintest.com/products-details.aspx?id=14]here[/url] (and in the ammonia section [url=http://www.completeleisure.ie/elements/download/palintest_comparitor.pdf]here[/url]) implies that these tests are designed for non-chlorinated waters.  If your specific test instructions didn't say to first measure monochloramine and account for that in the test, then monochloramine interefered with your result -- in fact, you likely just measured monochloramine (and technically, according to [url=http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TF4-4S7SV5B-2&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=a61791f39ab386ce23efd26e945c9262]this link[/url] it's literally monochloramine, inorganic chloramine, and not any organic chloramines such as chlorourea).  The Hach instructions give a nice summary of the test method as follows where it is clear that the test is really for monochloramine and that one creates monochloramine from ammonia using chlorine (that clearly reacts quickly since you only have to wait for 2 minutes at 25C or 77F):

Summary of Method

Monochloramine (NH2Cl) and “free ammonia” (NH3 and NH4+) can exist in the same water sample. Added hypochlorite combines with free ammonia to form more monochloramine. In the presence of a cyanoferrate catalyst, monochloramine in the sample reacts with a substituted phenol to form an intermediate monoimine compound. The intermediate couples with excess substituted phenol to form a green-colored indophenol, which is proportional to the amount of monochloramine present in the sample. Free ammonia is determined by comparing the color intensities, with and without added hypochlorite.

Figure 1 in [url=http://www.hach.com/fmmimghach?/CODE%3AL61351472%7C1]this PDF file[/url] shows the chemical reactions in the test where the first step is to convert any ammonia to monochloramine.  It should be obvious that if you already have monochloramine, then that is going to be additionally measured in the test.  It should also be obvious that the test itself counts on the fact that the first step, where ammonia and chlorine combine to form monochloramine, occurs quickly.

Also, if you have no chlorine in the pool water, then obviously any ammonia will persist as ammonia and will get measured as such.  It looks like one pool may have had that situation.  It looks to me like you ended up measuring the amount of monochloramine and not ammonia in the water, except possibly for the pool that had "no chlor" (what did you mean by this -- no chlorine?).

Ammonia is typically measured as mg NH3-N / L which is units of atomic nitrogen.  Monochloramine is typically measured as mg Cl2 / L which is units of chlorine gas equivalent.  There is roughly a factor of 5 difference in these measurements.  That is, 0.2 ammonia results in 1.0 monochloramine.  If your measurements of 5+ ppm ammonia were correct and measured in atomic nitrogen units, then if chlorine were present this would result in 25+ ppm monochloramine which seems unlikely.  Your "Andy" measurement was high at 5.65 yet used zeolite and said "no chlor" which I presume means no chlorine.  If that is the case, then with the zeolite there should not have been such a high ammonia so I strongly suspect that you were in fact measuring monochloramine in your tests and not ammonia.  Are you sure you did the test correctly?

The Nessler method (see [url=http://www.ungiwg.org/openwater/?q=node/82]here[/url]) does not get interference from monochloramine since the sample is dechlorinated [EDIT] actually, not true -- I see that it too gets interference from chloramines, probably because dechlorination converts monochloramine to ammonia [END-EDIT].  The Nessler reagent uses mercury, however, and is a more complex test to perform.

If I assume that you did the test incorrectly (or used the wrong test -- one that was not designed for chlorinated waters) and instead measured monochloramine, then your small sample does indicate a possibly lower likelihood for monochloramine (at least as measured) when zeolite is used, at least when chlorine is present.  Remember that I said that it was possible for a finer filtration to remove more organic precursors that could form chloramines.  That would be somewhat consistent with your data, though any filter with finer filtration would theoretically have the same result.  In other words, it doesn't have anything to do with ammonia absorption in the zeolite.

Can you give more specific details about how you did the test and distinguished between monochloramine and ammonia?  Did you tell your contact at Palintest that you were going to be testing swimming pool water that was chlorinated and therefore could contain monochloramine and whether their test would be interfered by this or, in effect, measure the sum of ammonia and monochloramine?  Do you have any links or references to the "vast body of Doctorial research" you refer to?  Also, why were so many pools "green" in your comments?  Do you mean they had algae?  Pools with algae and with chlorine (though obviously too low for the CYA level) will often measure high in Combined Chlorine (CC), mostly from monochloramine.

As for how fast chlorine combines with ammonia to form monochloramine, it's only a few seconds when the chlorine is strong due to no CYA in the water.  When the FC is roughly 10% of the CYA level, then the reaction is 90% complete in a little under one minute at 25C (77F) temperature.  The chlorine that is typically used in the indophenol test is typically Dichlor or some mixture of hypochlorite with CYA in order to slow down the reaction since you don't want to end up oxidizing the monochloramine during the time of the test.

Richard

[chem geek]

[quote user="teapot"]

The reason why Zeolites can filter out Ammonia is due to the ion exchange that takes place inside the filter, bearing in mind that water companies add somwhere in the region of 0.5mg/litre to the supply water it's not surprising its found in the pools. The majority of ammonia comes from the bacteria that convert Urea that comes from humans.

[/quote]

No one is disputing that zeolite filters out ammonia.  The issue is whether ammonia persists long enough in the presence of chlorine in order to be filtered out (it doesn't).

Water supplies do not add ammonia alone.  Those water companies that no longer add chlorine as a residual now add monochloramine (rapidly formed from a combination of adding chlorine and ammonia).  A recent study comparing chlorine and monochloramine effects in water supplies is [url=http://www.medicalnewstoday.com/articles/64342.php]here[/url].

Also, as described on p. 62 (PDF page 85) [url=http://www.who.int/entity/water_sanitation_health/bathing/bathing2/en/]here[/url], the largest nitrogenous component of sweat and urine is urea, followed by ammonia.  It is true that bacteria can convert urea to ammonia, but in a properly sanitized pool (i.e. one with residual chlorine) this should not happen since bacteria are quickly killed by chlorine.  Instead, chlorine oxidizes the urea, though this happens rather slowly taking many hours to days (though may be accelerated by UV from sunlight).  Chlorine oxidation of ammonia is much faster taking hours (at typical chlorine levels with CYA in the water).

Richard

[buckdendave]

Richard.

I'm impressed - I know a bit of chemistry and can just about follow some of your messages.  How you've got the time I don't know.

However, just to add something else to the pot.  Some French Water Cos, especially in the South, but also in isolated places elsewhere, are not using Chlorine or Chloramines as the sanitiser, they are using Chlorine Dioxide.  It's fairly commonplace.  Maybe you know this?

They do it because it is extremely effective at low dose levels and doesn't form chloramines - therefore the quality of water (taste) is considerably better - it really does make a big difference.  Of course there are a few drawbacks - one is that instead of chloramines you get other things that may be no more healthy.  And it is, of course a very powerful oxidising agent which can be quite destructive.

What happens in pool water, you can probably predict better than I.

Dave

 

 

[Théière]

[quote user="buckdendave"]

What happens in pool water, you can probably predict better than I.

Dave

[/quote]

It kills the algae and some bacteria then breaks down into chlorite which is not harmful.

[chem geek]

Chlorine dioxide is a good water treatment alternative.  The EPA has a good summary on its use [url=http://www.epa.gov/ogwdw/mdbp/pdf/alter/chapt_4.pdf]here[/url].  Where we live, monochloramine is used as a residual, but we have an activated carbon water filter that removes it (and it used to remove chlorine when that was used insetad of monochloramine) so the water tastes fine after the filter.

In fact, were it not for chlorine dioxide being so sensitive to breakdown in sunlight and it being difficult to dose/administer (especially in ways that avoid forming chlorate), it would be used in more pools as well.  Since it's so much better than chlorine at killing Crytpo, I've suggested using sodium chlorite added to chlorinated water that has CYA in it (that combo produces chlorine dioxide) as an overnight "shock" after a fecal accident since it can be used at 1 ppm over 8 hours, but since I'm pretty much a nobody, I don't think anyone is considering this.  With chlorine alone, one has to get to 10 ppm for 25 hours and that's without CYA in the water -- with CYA, the use of chlorine to shock after a fecal accident starts to become impractical.  See the [url=http://www.cdc.gov/healthyswimming/pdf/Fecal_Incident_Response_Recommendations_for_Pool_Staff.pdf]Fecal Incident Response Recommendations for Pool Staff[/url].

Richard

[buckdendave]

Generally correct but the safety of chlorite is a matter of some debate I think (in drinking water).

I thought about its potential use in pools through adding sodium chlorite, but haven't taken that step, and wouldn't recommend it.

The trouble with ClO2 is that it such a powerful oxidising agent that it has the ability to be destructive - for the same kind of reason that its so effective at dismantling pathogens.  We have been doing a lot of work with it in our test loops and it has the ability to destroy the loops at any significant level, especially as temperature rises.  You can be sure that any gaskets or seals are going to be attacked PDQ, for example.  Everything has to be fluoropolymer based if its going to last.  (Yes I'm a polymer chemist)

Dave 

 

 

[Théière]

As you say buckdendave its great at dismantling pathogens and its also water soluable as are we humans so it will enter our system through the skin in a swimming pool. Not a problem (alegedly) when consumed as the stomach acid and bial will preserve us.

[chem geek]

[quote user="buckdendave"]

The trouble with ClO2 is that it such a powerful oxidising agent that it has the ability to be destructive - for the same kind of reason that its so effective at dismantling pathogens.  We have been doing a lot of work with it in our test loops and it has the ability to destroy the loops at any significant level, especially as temperature rises.  You can be sure that any gaskets or seals are going to be attacked PDQ, for example.  Everything has to be fluoropolymer based if its going to last.  (Yes I'm a polymer chemist)

[/quote]

Thanks Dave.  That's good to know.  Since fecal accidents with loose stools are somewhat infrequent, I would hope that a shock with 1 ppm chlorine dioxide wouldn't be too destructive to equipment, but I see your point that it wouldn't be good as a regular sanitizer even if its other problems were solved.  I actually got the idea of using sodium chlorite by noticing that there were drinking water sanitation tablets sold in camping stores that used a combination of sodium chlorite and Dichlor.  After looking up the chemistry, I then noticed that there used to be sodium chlorite products (tablets, I think) to add to pools to produce chlorine dioxide, but I also noticed these pool tablets aren't available anymore.  This is probably due to the problems you mention as well as the others I referred to.  One also has to carefully dose the chlorite with the chlorine or else too many by-products are formed.

For an overnight shock after a fecal incident, the idea would be to either let sunlight breakdown the chlorine dioxide or one would use a reducing agent (dechlorintaor) before adding chlorine again.  The FC level for a Crypto kill using chlorine is 10 ppm FC with no CYA for 25 hours.  I suspect that won't be very good for pump seals or other components either.  What was the chlorine dioxide concentration when you saw problems and how long was the exposure?