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Dechlorination
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Author:  fransjoe [ Aug 5th, '17, 15:38 ]
Post subject:  Dechlorination

I was wondering what I could use for dechlorination. Here, my municipal water uses chloramines to disinfect the tap. I know a lot of the products sold in pet stores for fish are not to be used for food growing, so what can I use as a good, effective substitute for these chemicals? I've heard vitamin C can do it, another option was to hyperchlorinate the water with bleach or pool chlorine and just let it dissipate on its own. Please help...

Author:  Mr Damage [ Aug 5th, '17, 19:09 ]
Post subject:  Re: Dechlorination

Good aeration in an open top tank with exposure to sunlight will breakdown the chloramines quickly.

Author:  scotty435 [ Aug 6th, '17, 02:02 ]
Post subject:  Re: Dechlorination

You can also get away with a 20% water change without trying to remove the chloramines. How long it takes is going to depend on your water supply and how much they put in. Page 62 of this book, if you can get to it, gives you some information about the aeration and sunlight options - https://books.google.com/books?id=8cv36t8mOEwC&pg=PA62&lpg=PA62&dq=removal+of+chloramines+by+sunlight+and+aeration&source=bl&ots=hZnzk8VqZl&sig=hiZNOZ8zecYO_ubklVyH2itIse4&hl=en&sa=X&ved=0ahUKEwjG96yIy8DVAhVMxmMKHXwtDVUQ6AEIajAJ#v=onepage&q=removal%20of%20chloramines%20by%20sunlight%20and%20aeration&f=false.

Author:  Markk786 [ Aug 10th, '17, 11:12 ]
Post subject:  Re: Dechlorination

Hi,
how long should I dechlorinate..?

Author:  Mr Damage [ Aug 10th, '17, 17:46 ]
Post subject:  Re: Dechlorination

I have it on very good authority, from two leading hydroponic chemists, one who manufactures and sells a monochloramine based sterilising product, and the other who worked in the chemistry department of a leading university for over 20 years, that with good aeration and exposure to sunlight, the Chloramine would most likely have disassociated into Ammonia and Chlorine within 24hrs, definitely within 48hrs. Supposedly the Chlorine then only takes around 6 hours to gas off with good aeration, so if you allowed 24hrs you should definitely be safe.

Author:  dstjohn99 [ Aug 11th, '17, 05:10 ]
Post subject:  Re: Dechlorination

Mr Damage wrote:
I have it on very good authority, from two leading hydroponic chemists, one who manufactures and sells a monochloramine based sterilising product, and the other who worked in the chemistry department of a leading university for over 20 years, that with good aeration and exposure to sunlight, the Chloramine would most likely have disassociated into Ammonia and Chlorine within 24hrs, definitely within 48hrs. Supposedly the Chlorine then only takes around 6 hours to gas off with good aeration, so if you allowed 24hrs you should definitely be safe.


Interesting, I thought the premise of chloramine was that it was tenaciously stable. Good to hear that it can be broken down by normal means. Has anybody tested this in their AP system? I currently use Prime to de-chlor water that I add to my top up system of rainbarrels. I would like to use the aeration / sunlight method instead.

Author:  Mr Damage [ Aug 11th, '17, 11:28 ]
Post subject:  Re: Dechlorination

dstjohn99 wrote:
Interesting, I thought the premise of chloramine was that it was tenaciously stable.
Yep, when not exposed to UV, which is why it tends to be used in pipelines and tanks, where water is being pumped long distance or stored for extended periods. It also depends on what form of Chloramine is being used, there is some good info in the paper Scotty linked too. Municipal water supplies mostly use Mono-Chloramine.

An easy way to test if the chloramine bond is being broken is to use a Total & Free Chlorine test kit. As the Chloramine breaks down more of the Chlorine will show as Free Chlorine and less as Total Chlorine, and ultimately there should be no (or very low*) Chlorine reading. *Supposedly not all Chloramine will always disassociate, occasionally a very small amount may stay bonded and still show in Chlorine tests, but supposedly it's not enough to be of any concern. Reading I've done would suggest that in most situations it's such a small amount that it can only be measured with digital Chlorine readers.

To test accurately with a Total & Free Chlorine test kit, the Free Chlorine reading should be taken at about 15-20 seconds and the Total Chlorine reading should be taken after 5 minutes. The difference between the two readings will tell you what's happening with the Chloramine level in your water.

Author:  scotty435 [ Aug 12th, '17, 03:33 ]
Post subject:  Re: Dechlorination

Ammonia in the water your going to add could still be a problem. If the system water you're adding to is high pH, high temp the ammonia left in the change out water will convert to the more toxic form. Give this a bit of consideration if you're making a large change - might do it gradually over a couple of hours to let the biofilter do it's work if that's an option.

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