Chloramination Persistence

[waterdrop]

I'd like to report on a little informal looking around I did on chloramination:

(Note: there are at least 2 long threads about getting chlorine/chloramine out of your tap water - I'm not looking to repeat that here.)

Background: Some years ago we had a goldfish in a 2.5 gallon tank and I used to handle the weekly water changes by always filling a plastic milk jug with tap water for the next week's change and keeping it in an under-sink cabinet. There was no top so the chlorine could gas off. Having week-old water felt good to me from the standpoint of temperature matching as well as clearing of chlorine gas.

Chloramine Then: During those years our local water authority announced that they would begin experiments involving alternating the age-old chlorine gas treatment with a new method called chloramination (chloramination is familiar to most hobbiests and the chemistry should be available with searches here). There were warnings to aquarists to replace their de-chlorination treatments with new ones that handle chloramination. I got the new stuff and began treating my jug at the beginning of its week of sitting. Chloramines were said to persist in water much longer than chlorine.

My look around: Since I am returning to the hobby after many years to help set up my son's FW tank I decided to revisit this question. I did some searches and read some U.S. EPA documents about this and a number of other related research papers. I was specifically looking for persistence times for the residuals of chloramines in public drinking water systems. I was not able to find papers that made reference to specific numbers of days - they all simply made comparitive references saying that chloramines persist much longer in the water than chlorine. (In fact this is one of the attractions of this bacterial disinfection method of course.)

Here's a typical example of chloramination answer for hobbiests by a water agency:
"Can home remedies for treating aquarium water such as boiling water, using salts and letting water sit still for a few days remove chloramines?
NO. Home remedies such as boiling, using salts, and having water sit still are not sufficient methods to remove chloramines. Unlike chlorine, which only takes a few days to evaporate when sitting still, chloramines remain in water for a much longer time. The best way for fish owners to remove chloramines is to use a water conditioner that contains a dechloraminating chemical. The chemical is available at pet supply stores."

Chloramine Now: My local water authority and several authorities that are geographically around us have all accepted chloramination as a good technique and now it is the year-round treatment except for March, in our case, when they go back to chlorine and flush the water mains out. I think use of the new technique is growing in many places.

Tap water, water changes and filter bacterial populations: I've read that there are differences of opinion about how much of a filter bacterial population will be wiped out or how much the fish themselves might be harmed by -not- treating the new water added in a water change. It may turn out that there are good arguments by experienced aquarists that untreated tap water is ok to use but as a newbie I've been unable to assess these competing arguments.

My Conclusion: As a beginner I've decided to join what I perceive as the majority and always treat the new water with a dechloramination/dechlorination product in my weekly partial water changes. I plan to ask this forum some related questions but maybe because of too much coffee this morning just decided to post this as a little newbie service.

~~waterdrop~~

 

[backtotropical]

Hi Waterdrop,

First off, i'd like to commend you for being so thorough in your research. Many aquarists just jump in with both feet, often with disastrous consequences.

Regarding chloramination, from what i have read, there are arguments for not dechlorinating / dechloraminating tank water at all. The main points of this argument being that the de-nitrifying bacteria which we have come to know about through the hobby, is quite often found in our tap water. This would suggest that there are chlorine resistant strains of the bacteria which feed off the ammonia in the chloramine (chloramine is chlorine and ammonia). This would suggest that dechlorinating / dechloraminating can be a waste of time and money with regard to the survival of our filter bacteria. It is also used as an argument against the old rule of never washing filter media under the tap, as it would suggest that tap water does the bacteria little or no harm.

That said, i believe that less than half of tests on tap water were positive for our beloved bacteria, making not treating your water somewhat of a gamble. It will depend largely on the water company, and whether they use chlorine or chloramine. I would think that a water company who use chlorine, not chloramine, would provide water with no filter bacteria present as there would be no food for them to survive on (ammonia). I personally use dechlorinator religiously, as many do. It is easier than testing for chlorine, chloramine and de-nitrifying bacteria before every water change, because as you have said, the water companies can chop and change their methods.

The effect on our fish has to be factored in to this too, and our fish won't jump for joy when they find untreated chlorine in their water.

Hope this is a bit food for thought. I'm sure many others will have a contribution to this thread.

Regards

BTT

 

[waterdrop]

OK, I've continued to find some more links about chloramination (which I hope to share at some point although they may already be pinned here somewhere) and I finally found a statement I've been looking for:

A fair amount of the chloramine problem dissipates from water allowed to stand for a week.. However the statement I found said that a number of water authorities have done checks on this and have found that this is not always the case and often *chloramines can be found (whether in significant concentrations remains to be seen) after a week's time*.

I realize that it is now standard practice to Python or pour your fresh tap water either directly into your aquarium or into a premix container and hit it with a dechlorinator but...

Question for the forum: Any of you out there feel or have evidence that there are OTHER benefits to shelving your tap water for a week prior to using it in an aquarium water change? I mean benefits other than temperature leveling or chlorine gas release? Are there OTHER chemicals that might free themselves with aging?

-waterdrop-

 

[waterdrop]

OK, I've done a couple more experiments. Since Chloramination involves both chlorine and ammonia I decided to see whether there was a difference in the ammonia level of new tap water just from performing the dechlorination process.

I took a fresh gallon of tap water (my town uses the chloramination process) and tested the ammonia level with my api test kit. It matched most closely with 1ppm (maybe a little lower) of ammonia. I then dechlorinated the gallon. I tested for ammonia again and compared colors with the previous non-treated sample. There was a visible color change, a drop in ammonia level.

I repeated this sequence twice and observed the same thing both times.

It was kind of interesting that none of the four test tubes involved ever looked like the ammonia level was getting all the way down to 0 ppm.

Anyway, just another little observation to file away for anyone doing a chloramination search on the forum someday.

~~waterdrop~~