Why Are We Still Using A Dechlor During Water Changes? Chlorination Methods No Longer Used Nowadays!

Do you still have chlorinated water where you live?

  • Yup!

    Votes: 9 64.3%
  • Nope!

    Votes: 1 7.1%
  • Not sure.

    Votes: 4 28.6%

  • Total voters
  • Poll closed .

Mr. Anonymous

Good evening,

I was curious about this and really surprised it hasn't been talked about yet but, well, here it goes...

Why does the entire world use dechlor (ie: Seachem Prime, etc.) if there is NO CHLORINE in our tap water nowadays? For example in an OC Register article in Aug. 28, 2008, Updated Aug. 21, 2013, here it states how "ozone gas" also known as "ozone" will be used to treat our tap water in the entire Southern California metropolitin water district in which treats over 420+ million gallons of water per day, and this new method will be more effective, safer, and cleaner than chlorine methods, and that this will become effective sometime in 2012. So by now who knows what is used to treat our water but clearly chlorine is old school and not used anymore in most of the major cities we live in. So why are we using dechlors such as Prime, API, etc. during water changes?

Maybe it's just that some old cities that aren't up to date with the times still use chlorine to treat their water but what about the rest of us who live in the real world? Are there hidden benefits I don't know about when using these types of products during water changes. I could see the reason for keeping Prime around for emergencies but what if I don't have any chlorine in my tap water? Do I need to still use it for water changes if I live in SoCal?

Also I want to just mention in that my fish are and have always been so used to the tap water (with added Prime) that I could do 85%+ water changes a week or even 100 times a day and in my entire 10 years of keeping fish, never had I ever had a fish seem die or even seem stressed when doing anything like that. So it makes me think what the heck ever are we ever going by when we say more than 25% COULD KILL your fish? Etc. And what about all these special procedures and rules we all seem so eager to go and obey by such as "Treat ALL THE WATER you put in your tank before you put it in!" Etc. And the chlorine test kits we use, even though there hasn't been chlorine in my tap water for almost a decade etc?

For me and my fish, I don't let the water get so bad and infested with fish pee/poo and whatnot that its any different than the water I gave them last week. And my fish are the happiest little sons of guns in the world! They love me, and they love life! So so much! They also know that at all times they are safe and in good hands with me 24-7, and they appreciate that. Anyway, this is more about the non-chlorinated water and still using dechlor and not about my fish, but I just wanted to mention that my water never gets bad enough (or different enough) that if I changed more than 25%-50% that my fish would stress out or worse.

Still don't see how this stuff not been discussed, like at all.

Thanks a lot for reading and possibly contributing!


Pure chlorine may not be in nearly as much as it used to be but chloramine is still widely used thus the need for dechlorinators. As far as chlorine test kits go I've never actually heard of anyone using these in aquariums. I know I dont.

And for the water change thing I'm not sure I've seen people saying you can't change more than 25% of the water at a time. It's not the best idea for shrimp tanks or some particularly delicate species of fish but I don't think there's much of a debate on whether or not you can do water changes of greater than 25% without killing your fish. I change out 80% of the water in my fry tanks almost daily.


Yeah, most here use chloramine, so technically I guess most people are using dechloraminator.


Prime also detoxifies any heavy metals present in the tap water as well


If the new methods are being used where you live, and you can confirm no chloramines are present, you don't need a conditioner. You would have to determine that first.
Where I live, surrounded by water, we never switched to chloramines, and still run old school chlorine in our fairly good tap. I confirmed this by calling the city water department. As is usual, if you bother to seek info, it is probably available. A lot of cities have web sites that detail their treatments.
There will always be issues with company reps and forums, and with people who are nervous and spend as a result. These are fertile marketplaces, and I even see people pushing Prime and other conditioners for untreated well water. I suppose if you do a test (not with a toy kit but in a lab) and it shows the presence of heavy metals in safe for drinking levels, you might want to neutralize them, but in general, no one with well water needs a conditioner, ever. The companies that sell the conditioners need a market, so we have many many members convinced that since the chemicals are reasonably inexpensive, they will pour them in because they are afraid not to.
Dealing with simple chlorine, if I do less than a 25% water change, I aI'm my hose at the tank wall and the agitation gasses off the chlorine. Above 25%, and I use a dechlorinator. I have fry from 12 species right now, most from wild caught parents and several considered super delicate. So no harm is done.
I suspect that if you lived on the banks of the Amazon with a pump right into the deepest, cleanest flow filling your angelfish tanks, someone would try to sell you a conditioner.


My county's water company adds chlorine. Sometimes I think they just don't care and add whatever they feel like because every so often, the water stinks to high heaven.


Probably all depends on where you live -if they don't use chlorine where you live, then I guess you don't need to use it Having said that though, I don't use it in my outdoor tub ponds even though our water (in Australia) is chlorine treated.. (I do use it in my indoor swordtail aquariums though). So maybe some hardy types of fish can tolerate the chlorine levels, or it's not actually enough to affect them? I'm still not willing to take a chance with my aquariums, but my pond fish are healthy and have been living in 'chlorinated' water for years


EPA requires all public water systems in the US to have a chlorine residual in drinking water.


Yeah here in South Florida I believe we have chloramine in the tap.

The prevailing idea about water changes (from my experience) is that IF you go a long time between water changes it's probably not a good idea to do an enormous one bc your parameters may have shifted (pH, hardness, etc), and you risk shocking the fish. If you do frequent water changes, it doesn't really matter what volume you do.

As for "special procedures and rules we all seem so eager to go and obey by", if you do have chlorine or chloramine in your water, then "Treat ALL THE WATER you put in your tank before you put it in!" is sound advice and not unreasonable at all. Why would you want some chlorine to remain in your tank?


[QUOTE="Jennywren, post: 2809450, member: 70792" Why would you want some chlorine to remain in your tank?[/QUOTE]

My reasoning is that I found my water hardness going up from the Sodium thiosulphate that dechlorinates. The very tiny residual amounts of chlorine vanish quickly, and softer water is better for the fish I breed.
The difference is minimal, but it is hard to reduce mineral content to begin with.
I go by observation, and have never seen any ill effects, never had lifespan problems (cardinals reaching 10 years and Bettas 7) and have been breeding fish the whole time I've been doing this (200 species, approx). Chlorine doesn't remain - it vanishes into the air quickly, especially as I filter well.
I have a lot of tanks, and in my country a 4 ltr bottle of prime would cost me $120, plus shipping. Chlorine dissipates harmlessly, and I don't have chloramines, which stay around. Why use an unnecessary additive?
I would not counsel a newcomer to do this, as you must have a hose to the tank to succeed at it. With buckets, it would be a fiasco.


I'm in Southern california, in San Bernardino County, and my tap has chlorine. I treat it with Prime, I do water changes weekly. It's as simple as that
  • Thread Starter

Mr. Anonymous

aquatickeeper said:
I'm in Southern california, in San Bernardino County, and my tap has chlorine. I treat it with Prime, I do water changes weekly. It's as simple as that
Yeah! I hear that San Bernardino County has the worst tap water in SoCal. Some say they would rather drink urine. I'm sorry about that, but if you want I can send you some of my urine that came from clean Orange County tap water and it will be much better than yours.


We are on our own private well and our water is excellent. There is no chlorine or chloramine in our water, but I still like using Prime. Call it a habit but I feel weird not using something Plus it doesn't hurt my guys.
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I'm in china so who knows what's in my water so I dose double with my dechlorinator in buckets and let it sit before I add it to my tank


Once a year the city warns us they're chlorinating the lines and it smells a little like bleach for a day or two.


Our water is always treated with chloramine. We just had a notification from the water company that they are doing a temporary switch to chlorine and will switch back sometime soon to chloramine. I always treat with a dechlorinator too.
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