De-chlorination... is is necessary?

[MarkO1]

Does chlorinated water contain any forms of chlorine that could be harmful to fish or invertibrates? Just wondering since I've been topping off with water right out of the tap.

 

[dug5921]

i've been using tap water with very litte side effects (other than diatoms). i just add a little water conditioner that supposedly neutralizes contaminates. i do plan on going to r/o for my water changes, because the diatoms are starting to bug me.

 

[esmithiii]

Depending on the quantity that you add at one time and where you live it may or may not be ok. Chlorine in great enough concentrations is deadly to fish and invertibrates. (If you want proof, pour a cup of bleach in your tank and wait 15 minutes) The concentration in tap water in the US is usually enough to kill freshwater fish if undiluted. When you add top off water, however you are usually adding very little water to a large volume of water. If you fill your top-off resevoir with tap water and it tops of a little at a time you will have no problem (after 24 hours most the chlorine is gone anyway.) If you add a couple of gallons at a time to a small tank, then you could have problems.

As for not even "putting things in my tank that have been washed with tap water and not dried" that is a bit obsessive-compulsive to say the least.

Ernie

 

[esmithiii]

My previous post addresses chlorine only. Other things can enter your tank through tap water. The most notorious are phosphates and silicates, which can cause algae growth. I personally use RO/DI water and am a bit obsessive-compulsive myself.

E

[ October 29, 2001: Message edited by: esmithiii ]</p>

 

[MarkO1]

OK, so I take it that the chlorine the City adds is in a different form that the chloring ion in NaCl (salt)?

 

[SB-129]

Whoa! I've never heard of anyone just pouring (or dripping) tap water into a reef tank...

Chlorine is of course a concern but there are many other potential contaminants, aren't there? Heavy metals? Copper from old pipes? Organics? I mean, if it works for you, great, but I'd never try such an experiment. I am even hesitant to put things in my tank that have been washed with tap water and not dried. I use only RO/DI for makeup.


Am I totally paranoid? Do others use tap water with no problems?

 

[gbtower]

Chlorine is definitely harmful. That's why it's used to keep tapwater "clean". Just depends on its concentration. So if you're adding only a little bit at a time, any effects would probably not be noticeable. But like SB said, I'd worry more about the other nasties. They don't evaporate so the more tap you add, the more nasties you've got. It's only a matter of time...

 

[Anonymous]

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote

OK, so I take it that the chlorine the City adds is in a different form that the chloring ion in NaCl (salt)?

Why yes, it is very different. When two elements are bonded to form a new molecule, they become a whole new substance. The chlorine atom does not separate from the sodium (Na) in your tank.

In fact, NaCl is the molecule that is often used to illustrate this exact idea in chemistry classes. Na and Cl are both highly dangerous elements. Cl is very poisonous, and Na is highly explosive upon contact with water. But combined, they form a harmless salt.

 

[bensenvill]

An interesting note is that the ammount of chlorine in water changes considerably. Depending on the water quality at the pumping station, depends on the ammount they add to the water.

 

[MattM]

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by mulberry:
<strong>The chlorine atom does not separate from the sodium (Na) in your tank.</strong><hr></blockquote>

This is incorrect.

Virtually all elements is saltwater exist as ions. When sodium chloride dissolves in water, it breaks up into sodium ions (Na+) and chloride ions (Cl-).

As far as MarkO's question about the difference between chlorine gas and the chloride in salt, yes they are different.

Chlorine gas (Cl2) is used to disinfect water. After chlorination, carbon or reverse osmosis is used to remove the chlorine. There is almost no chlorine left in chlorinated water. What is left in the water is called "Disinfection byproducts".

Here are their allowable levels from the EPA:

4 ppm Chlorine (Cl2)
4 ppm Chloramine (NH2Cl)
0.8 ppm Chlorine Dioxide (ClO2)
0.8 ppm Chlorite (ClO2-)
250 ppm Chloride (Cl-)

So the most common residual from chlorination, by far, is chloride - that same as that found in salt.

 

[MattM]

P.S.

Concerning esmithiii's comment about bleach, that's another different form - sodium hypochlorite (NaOCl).

What a tremendous difference one oxygen atom can make.

BTW, in many parts of the world, sodium hypochlorite is used instead of chloramine for water disinfection. In the right amount it works the same.

 

[MarkO1]

OK, OK, OK... I give...I just purchased a 50 GPD RO/DI unit.