Is Chlorine Really Dangerous?

[JamieH]

ok... don't flame me, i'm mearly passing on an opinion.

I was speaking to a guy who keeps fish today and he told me that in established tanks with lot's of disolved organics, that using a dechlorinator is a waste of money.

His theory is, that most dechlorinators just bind an organic compound with the chlorine in the water - many use aloe vera. Effectively, in a mature aquarium there is plenty of organics in the water, and provided you aren't changing huge volumes of water, the chlorine is used up almost as soon as you pour it into the tank.

Does anyone on here know enough about chemistry to prove of disprove this?

 

[chibi]

I'm no expert in any way, but I can remember hearing if you pour water with chlorine in it, the bubbling when it hits the water will release some of the chlorine into the air. I still don't risk it. I think it's much better to pay $4 for a bottle of dechlorinator that will last me 5+ months than to risk killing all my fish.

 

[smurfyy_2k3]

the chlorine will evaporate after 24 hours so in a sense if you have spare room yeah you can remove chlorine that way, as for the organic matter in the water thing, well not everyone uses live plants so that severely reduces the amount of organic matter to start with, also how many plants actually produce aloe vera, not alot, also my bottle of tapsafe contains aloe vera and it isnt there to bind its to

a healing coating for delicate skin and gills

 

[JamieH]

the chlorine will evaporate after 24 hours so in a sense if you have spare room yeah you can remove chlorine that way, as for the organic matter in the water thing, well not everyone uses live plants so that severely reduces the amount of organic matter to start with, also how many plants actually produce aloe vera, not alot, also my bottle of tapsafe contains aloe vera and it isnt there to bind its to

a healing coating for delicate skin and gills

by organic matter i mean disolved organics, not plants.

the aloe vera is there to do both things....

 

[Betta5]

But if you leave it just the chlorine goes what about heavy metals and chlorimine (sp)

 

[Dave Spencer]

Chlorine is in tap water will kill bacteria, therefore, it will kill bacteria in your filter. If your friend has been adding untreated tap water to his tank with no problems, then good luck to him. Personally, I always use a treatment that neutralises chloramines as well.

Water utilities are increasingly using chloramines because they are more stable in water and will not dissipate from water, so the 24 hours in a bucket method may not work.

If you want peace of mind, dechlorinate with a product that deals with chloramines as well. I use King British.

Hope this helps, Dave.

 

[MHunt]

The problem these days isn't really the chlorine. Chlorine like you say does dissipate from the water easily with agitation, and like you say can be neutralised with high level of dissolved organic compounds. Most water companies now use chloramines that are chlorine bound with ammonia. This is far more resiliant and stays in the water much longer and without treating the water before adding it to the tank, wouldn't necessarily kill the fish directly, but it would kill the biological filter, crashing the cycle. The resulting ammonia spike would almost certainly kill the fish.

If you can be certain that your water company does not use and is not planning to use chloramines, then yes there are alternatives to make the water safe for your aquarium. Otherwise it is wise to use a tap water conditioner to neutralise the chlorine and chloramines before adding the water to your tank.

 

[JamieH]

The problem these days isn't really the chlorine. Chlorine like you say does dissipate from the water easily with agitation, and like you say can be neutralised with high level of dissolved organic compounds. Most water companies now use chloramines that are chlorine bound with ammonia. This is far more resiliant and stays in the water much longer and without treating the water before adding it to the tank, wouldn't necessarily kill the fish directly, but it would kill the biological filter, crashing the cycle. The resulting ammonia spike would almost certainly kill the fish.

If you can be certain that your water company does not use and is not planning to use chloramines, then yes there are alternatives to make the water safe for your aquarium. Otherwise it is wise to use a tap water conditioner to neutralise the chlorine and chloramines before adding the water to your tank.

No one is really answering the question... yes chlorine WILL Kill bacteria... we know this.

the question is - do the dissolved organics in a mature aquarium actually bind the chlorine as fast as a commercial agent and therefore render it's effect negliable when doing small partial water changes

 

[smurfyy_2k3]

the question is - do the dissolved organics in a mature aquarium actually bind the chlorine as fast as a commercial agent and therefore render it's effect negliable when doing small partial water changes

not likely question answered even if it did i doubt the average aquarium could produce enough to dechlorinate a couple of buckets of water

 

[TolkienGeek]

I don't bother dechlorinate when I top the tank off, at most I'll put 2 liters in then. In my 29 gallon tank the chlorine dilutes and quickly evaporates. I do use dechlorinator when I do a water changes, however, mostly for the heavy metal binding benefits.

I doubt organic matter has anything to do with it. Chlorine is highly unstable and diluted as it is, the little bit I put in at top off is not going to do any damage.

 

[Bignose]

Actually, the more common dechlorination chemical is a sodium sulfer salt solution: sodium thiolsulfate

in basic water:
Na2S2O3 + 4CL2 + 5H2O --> 2NaHSO4 + 8 HCl
in acidic water:
Na2S2O3 + Cl2 + H2O --> Na2SO4 + S + 2HCl

The dechlorinators that treat chloramines usually have an agent that breaks the Cl-ammonia bond then the sodium thiolsulfate does its thing.

However, all that said, the guy you talked with may be right, though completely wrong as to why. It is becoming a serious problem that bacteria strains are becoming more resistant to chlorine and chloramines. Specificlaly, the bacteria that we culture as fishkeepers are amoung the worst offenders. Because they are resistant, chloramines don't kill them, and the resistant strains can actually use the ammonia part of the the chloramines. Unfortunately, by using it up, less chloramine is available to kill off the bad bacteria, like E. coli. In a mature tank, with lots of ammonia- and nitrite- oxidizing bacteria, most likely a resistant strain because they come in with your tap water and survived the chlorination at the water plant, that same untreated water is not going to affect them very much. A mature tank with lots of bacteria can probably sustain a 10% die off without it even registering on the tanks, simply because the bacteria grow back so quickly. 10% is just a number I threw out, I suspect it is probably less because of the resistances.

All that said, it is not like dechlorinators are expensive, and they also bind up heavy metals (though organics do a lot of that too), I'd just a soon take a simple, pretty darn cheap step and be safe rather than sorry.

 

[puddle_inc]

i always heard chlorine could kill fish very easily. isn't it kinda like putting a fish in a pool, just not as bad...

 

[andywg]

I know of two people on another UK forum who have stopped using dechlor iwthout any problems. One has chlorine in his tap water and the other chloramine. Both have had no problems after 6 months.

On the subject of how bad chlormaines are, Bignose found an interesting load of information the last time this was discussed:

Well, a quick perusal of the scientific literature came up with some rather surprising results.

Firstly, and most surprising to me, the problem ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) growing in water utilities' facilities is becoming a somewhat serious issue. The chloramine does in fact, promote the growth of AOB and NOB, with the consequences -- written is a nice non-threatening way as -- "...the addition of chloramines can lead to biological instability in a drinking water distribution system by promoting the growth of nitrifying bacteria..." and "The resulting reduction in chloramine residual and development of a microbial community in the distribution system lead to water quality deterioration and violation of drinking water regulations." I think that I might very well have put a little more emphasis on violations of the drinking water regulations.

Basically, because the AOB and NOB grow, they excrete other organic compounds allowing other bacteria to grow. At the very minimum, this additional bacteria will require more chloramine to kill it off, but then, more chloramine promotes more growth of AOB and NOB, and I think you can see where this cycle is going... Here is the really bad news, with this extra growth, all that stuff we don't want in there could grow now, like the coliform bacteria (E. coli -- think spinach), and viruses, and Guardia lamblia and so on. All of these are pretty strictly required to be below certain levels by the U.S. EPA, and similarly in other countries.

Secondly, the really interesting part is that in lab test after lab test, the recommended exposure times and concentrations of chloramines do their jobs. The chloramines in the lab kill off all the organics, including the AOB and NOB. However, at the utility side of the issue, nitrification episodes are rather commonplace. One recent study found 63% of U.S. chloramining utilities and 64% of Southern Australian utilities tested positive for nitrifying bacteria.

One hypothesis for the discrepancy between the laboratory studies and operating results is that there are AOB strains
growing in full-scale systems that possess a greater chloramine resistance than those studied in the kinetic experiments. Whether the AOB strains used in earlier kinetic studies are representative of significant strains involved in full-scale nitrification episodes has not been confirmed, since there are no published evaluations of AOB diversity in chloraminated distribution systems.

This quote, and the above ones, from Regan, Harrington, and Noguera: "Ammonia- and Nitrite-Oxidizing Bacterial Communities in a Pilot-Scale Chloraminated Drinking Water Distribution System" Applied and Enviromental Microbiology 2002. The study where the %'s came from was Wolfe et al. "Occurrence of nitrification in chloranimated distribution systems" Journal (American Water Works Association), 1996

In other words, the strains that are in the water utilities have become more resistant to chloramines, and can indeed use the ammonia present as sustenance.

And, back to fishtanks, where do the AOB and NOB come from in the first place? Well, if you used tap water, they probably came from your water utility, and if a resistant strain has grown there... that same chloramine resistant strain is probably now growing in your tank too. The Regan et al. study cited above and Regan et al. "Diversity of nitrifying bacteria in full-scale cloranimated distribution systems" Water Research, 2003, was among the first to use DNA sequencing to distinguish all the different AOB and NOB that are growing. Some of the names should be pretty familiar: AOBs Nitrosospira, Nm. oligotropha and NOBs Nitrospira, Nitrobacter

So, it seems that AOB and so on can become resistant, or at the very least, as mentioned in the above posts, the chloramine levels are certainly not designed to sterilize a colony of bacteria as large in number as we culture in our tanks and so chloraminated water probably is not going to ruin a fishtank.

All that said, I think I am still going to continue to use my conditioner. It is pretty cheap, and better safe than sorry. However, I am not going to fret if I forget, or if a water change is due up and I haven't been to the LFS lately to get a new bottle.

Oh, and of course, I will now be nice and worried about our water supply.

 

[JamieH]

I know of two people on another UK forum who have stopped using dechlor iwthout any problems. One has chlorine in his tap water and the other chloramine. Both have had no problems after 6 months.

On the subject of how bad chlormaines are, Bignose found an interesting load of information the last time this was discussed:

Well, a quick perusal of the scientific literature came up with some rather surprising results.

Firstly, and most surprising to me, the problem ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) growing in water utilities' facilities is becoming a somewhat serious issue. The chloramine does in fact, promote the growth of AOB and NOB, with the consequences -- written is a nice non-threatening way as -- "...the addition of chloramines can lead to biological instability in a drinking water distribution system by promoting the growth of nitrifying bacteria..." and "The resulting reduction in chloramine residual and development of a microbial community in the distribution system lead to water quality deterioration and violation of drinking water regulations." I think that I might very well have put a little more emphasis on violations of the drinking water regulations.

Basically, because the AOB and NOB grow, they excrete other organic compounds allowing other bacteria to grow. At the very minimum, this additional bacteria will require more chloramine to kill it off, but then, more chloramine promotes more growth of AOB and NOB, and I think you can see where this cycle is going... Here is the really bad news, with this extra growth, all that stuff we don't want in there could grow now, like the coliform bacteria (E. coli -- think spinach), and viruses, and Guardia lamblia and so on. All of these are pretty strictly required to be below certain levels by the U.S. EPA, and similarly in other countries.

Secondly, the really interesting part is that in lab test after lab test, the recommended exposure times and concentrations of chloramines do their jobs. The chloramines in the lab kill off all the organics, including the AOB and NOB. However, at the utility side of the issue, nitrification episodes are rather commonplace. One recent study found 63% of U.S. chloramining utilities and 64% of Southern Australian utilities tested positive for nitrifying bacteria.

One hypothesis for the discrepancy between the laboratory studies and operating results is that there are AOB strains
growing in full-scale systems that possess a greater chloramine resistance than those studied in the kinetic experiments. Whether the AOB strains used in earlier kinetic studies are representative of significant strains involved in full-scale nitrification episodes has not been confirmed, since there are no published evaluations of AOB diversity in chloraminated distribution systems.

This quote, and the above ones, from Regan, Harrington, and Noguera: "Ammonia- and Nitrite-Oxidizing Bacterial Communities in a Pilot-Scale Chloraminated Drinking Water Distribution System" Applied and Enviromental Microbiology 2002. The study where the %'s came from was Wolfe et al. "Occurrence of nitrification in chloranimated distribution systems" Journal (American Water Works Association), 1996

In other words, the strains that are in the water utilities have become more resistant to chloramines, and can indeed use the ammonia present as sustenance.

And, back to fishtanks, where do the AOB and NOB come from in the first place? Well, if you used tap water, they probably came from your water utility, and if a resistant strain has grown there... that same chloramine resistant strain is probably now growing in your tank too. The Regan et al. study cited above and Regan et al. "Diversity of nitrifying bacteria in full-scale cloranimated distribution systems" Water Research, 2003, was among the first to use DNA sequencing to distinguish all the different AOB and NOB that are growing. Some of the names should be pretty familiar: AOBs Nitrosospira, Nm. oligotropha and NOBs Nitrospira, Nitrobacter

So, it seems that AOB and so on can become resistant, or at the very least, as mentioned in the above posts, the chloramine levels are certainly not designed to sterilize a colony of bacteria as large in number as we culture in our tanks and so chloraminated water probably is not going to ruin a fishtank.

All that said, I think I am still going to continue to use my conditioner. It is pretty cheap, and better safe than sorry. However, I am not going to fret if I forget, or if a water change is due up and I haven't been to the LFS lately to get a new bottle.

Oh, and of course, I will now be nice and worried about our water supply.

cheers!

 

[Themuleous]

Thats very interesting and also slightly worrying. Just goes to show that nature always finds a way to get around what be do to try and control it.

Sam