Jump to content

Organic Chloramines


rmcderm313

Recommended Posts

Hi All,

I'm interested what folks on this forum think of the findings of this article from Aqua magazine.  It's general premise is that super-chlorinating to release chloramines only addresses inorganic chloramines and will leave behind any organic.

Article on Break-point Chlorination

If I read and understood correctly, even MPS will not address organic chloramines and the only way to get rid of them is by 'draining and dilution'.  Although the article does also mention that MPS might have advantages over chlorine in releasing less 'disinfection byproducts' (DPB's).

I've noticed a number of posters who super-chlorinate (and/or use MPS for that matter) but still have some undesirable combined chlorine readings.  I have a minor issue with this, but it's not been enough to worry too much about.  I haven't read in any of the responses a reference to possible organic chloramines being part of the issue that, if this article is accurate, you cannot get rid of.

I only stumbled across this article in the course of researching the break-point process and I have no concept of its accuracy.  It seems well balanced in it's approach, even pointing out that DuPont has a vested interest in pushing MPS.  I'm not trying to spread fake news, that is why I'm interested in the opinions of those contributors here who have helped me get my hot tub water chemistry in very good shape.

Any thoughts?

Thanks,

Rob

 

Edited by rmcderm313
mis stated
Link to comment
Share on other sites

  • 2 weeks later...

This is an old article on breakpoint chlorination (2011). It has been known for quite a while that breakpoint chlorination (shocking to 10 times the CC level ) does not work for several reasons, least of which is that it does not take into account the CYA level which has a direct impact on the activity of the chlorine added. Unfortunately, it is still taught in CPO courses and is ingrained in the industry along with several other fallacies that wont die such as 'walking' acid to lower pH vs 'slugging' acid to lower TA (doesn't matter, both have the same effect with the exception that 'slugging' acid can and will damage surfaces and equipment).

The article also talks about volatile disinfection byproducts and their negative health effects. However, this are really only a problem in INDOOR pools and spas (and to a lesser extent, covered outdoor spas)  with no exposure to UV from sunlight since these volatile byproducts will build up in the pool enclosure unless very effective air handlers are installed. In UNCOVERED OUTDOOR pools and uncovered spas they enter the atmosphere and the UV from sunlight also helps destroy them. This is why a properly maintained outdoor pool often will never need shocking.

MPS is of some use in indoor pools (as is the addition of UV) and in covered outdoor spas that have persistent CC over 1 ppm in reducing CC but it often cannot totally eliminate it. In a covered spa many of these undesirable volatile oxidation byproducts will gas off if you uncover the tub and run it on full aeration for aobut 15 minues of so before entering.

  • Thanks 2
Link to comment
Share on other sites

Thanks @waterbear for the reply. I was aware that the article was quite old, but I haven't been able to find much further written about the organic/inorganic chloramines.

Interesting timing, this has become more of a practical matter for me since posting this question.  I'm now struggling with a CC near 1ppm, and possibly even a bit over depending upon how stringent I want to be about a color change between the 2nd and 3rd drop. I'm using the K-2006 kit.

My spa is on an enclosed 3-season porch, so I am concerned a bit more than others on DBP.  I do open all the windows when I run the jets or use the tub at all, so ventilation is pretty good but there are no vents at the ceiling.  There is no UV that hits the water.

  • I've used the bleach/dichlor method on this fill, which was filled on January 16th. 
  • CYA is right around 30ppm. 
  • I did use 50ppm boric acid at fill.
  • TA has been consistent around 50.
  • Chlorine demand is reasonable. 
  • I do not use MPS and only bleach (after Dichlor to reach desired CYA)
  • I use bleach after every soak to ensure I start the next day with between 3-5ppm FC.  Sometimes I shoot a bit high and start the next day with between 8-10ppm.  We shower before using the spa every time.
  • I've been shocking every Monday with bleach.  16oz of 8.25% which bumps the FC to between 18-20 depending on how much we've used the spa over the weekend.
  • Water is crystal clear and only has a slight chlorine/chemical smell up close.
  • Up until recently pH has been right at 7.4-7.5 without effort, but in the last week it has climbed to 7.8. Not clear on why this happened.

Aside from the boric acid and some calcium to raise CH to 150ppm at startup (our water is soft), the only chemicals I have used are the Dichlor (to get to 30ppm CYA) and then bleach.  Today for the first time I added 2oz of Boric acid and 2 tbsp of calcium.  Where I've had to add some fresh water over time to keep the tub to a good level, I figured I should compensate for that loss for the fresh water and that maybe the additional Boric acid might help lower my pH a bit or at least provide a bit of an additional buffer.

Given all this, should I be able to get rid of that combined chlorine by 'shocking' with bleach each week? Or is it possible that in my situation I will not be able to get rid of it until I drain and refill. Is there anything else I can try?

Finally, so far we are not bothered by what might be greater than 1ppm combined chlorine.  Is there any danger in that? Or is it more that it might irritate some people's skin or eyes?  I have very sensitive skin so I'm surprised I haven't encountered an issue yet.

Thanks as always for sharing your knowledge.

Rob

 

 

 

 

Link to comment
Share on other sites

First, when you have borate in the water you pH will stay around 7.7 because the borate/boric acid buffer in conjucntion with the bicarbonate/carbonic acid buffer (TA) work together to settle the pH right around there. Keep your TA between 50-70 ppm and don't try to lower the pH below 7.6 and don't lower it until it climbs above 7.8 for the best pH stability.

As far as the CC goes, if it's staying around 1 ppm I wouldn't lose any sleep over it. If it is consistently higher than 1 ppm and bleach doesn't bring it down then MPS might be usedful but MPS has it's own set of problems, not the least of which is that it is a known sensitizer and many people develop dermatitis after soaking in it.

TEST your water before shocking. IF the CC is 1 ppm or less you really should not need to shock. If it is less than .5 ppm you most certainly don't need to shock.

  • Thanks 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Unfortunately, your content contains terms that we do not allow. Please edit your content to remove the highlighted words below.
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...