When to add de-chlorinator?

[kvr]

why/when to add de-chlorinator ?

First of all, congrats on all you guys/girls who keep this forum up and running, I can hardly wait to try all the facilities of this new software. I do however hope that it will be (and stay) possible to retrieve the old messages as well ! Thanks all !

Personally, I always add de-chlorinator to my buckets each time I do a water change. I also believe that chlorine and chloramine can cause fish deaths. It is however possible that most of the time, the concentration of chlorine/chloramine in the tap water is too low to have any immediate (lethal) effects, that however does not mean that the fish are not stressed with those low concentrations. Problems might however arise when your local water company decides to give their system a complete rinse and throws in larger amounts of chloramine in the water. If at that time, someone is just performing a water change, I bet that that person is gonna loose some fish.

I am not a specialist on this topic, but I did find some references on the effect of chloramine on fish health, for those who are interested :

Anderson, Frank G. 1995. Chemical dependence in the aquarium: are conditioners worth the cost? Yes... and no. FAMA 1/95.

Blasiola, George. 1984. Protecting aquarium and pond fish from the danger of chloramine. FAMA 4/84.

Herwig, Nelson. 1982. Toxic chloramine induced intravascular hemolytic anemia in fish. FAMA 10/82.

FAMA stands for Freshwater And Marine Aquaria magazine. This is not a peer reviewed journal, but is IMO of good quality.

Good information on chloramines can also be found in the Canadian Environmental Protection Act, 1999. This report deals with toxicological and environmental aspects of chloramine, including its effect on freshwater and marine fish (pages 24-28 are interesting !!!) If you'd like a copy, just let me know, I'll send you one.

From this reference, it says :
ninety-six hour LC50 values for fish ranged from 0.07 mg/l for coho salmon to 1.72 mg/l for carp. The lowest, no observed adversed effect concentration (NOAEC) for inorganic chloramines for fish was 0.0165 mg/l for the fathead minnow. The treshold for growth reduction in coho salmon was 0.011-0.023mg/l. The higher the temperature, the more toxic these chloramines seem to be.

Other examples, for killifish (100% mortality at a conc. of 1.20mg/l), stress in killifish was observed at 0.65 mg/l.

Drinking water treatment facilities achieve chloramine concentrations of between 0.01 and 4.8 mg/l at the source and troughout the distribution system. The average chloramine concentration in drinking water (at the source and throughout the system) was 1.0 mg/l in 1995 and 1996. The average minimum concentration were 0.61 and 0.60 mg/l in 1995 and 1996 resp. whereas the average max. concentration were 1.66 mg/l and 1.46 mg/l in the same years (Environment Canada, 1997). I haven't found values for other countries yet, but it would suprise me if the concentration would be that different.

For chlorine :

I also found some more information on its toxicity. In research performed by Dr. B. Sahli (toxicologist), working at the Virginia Department of Health (Office of Epidemiology,
Division of Health Hazards Control), I found that freshwater fishes and invertabrates show a wide range of sensitivities to chlorine. The LC50 (concentration at which 50% of the tested fish died) was 390ppb for a darter and 710ppb for a stickleback, for two kinds of trout, two types of shiner and a channel catfish, the acute values were between 45 and 90ppb. Species mean acute toxicity values for a crayfish, stonefly and amphipod were 266ppb, 400ppb and 673ppb respectively. Eleven species of saltwater fish had acute values ranging from 37ppb to 270 ppb. The coho salmon had a species mean acute value of 47ppb and the Atlantic silverside had a value of 37ppb.

As a comparison :

In the US, EPA guidelines require that tap water at any faucet contain a minimal chlorine concentration of .2 ppm (that's 200ppb), and stringently limits the concentration of bacteria (which may require more than .2 ppm chlorine to keep in check). Because chlorine breaks down over time, the chlorine concentration of the water that comes out of your tap will be lower than that put in at water plant. Thus, the exact concentration at your faucet depends on how far you are from the water plant, how long it takes the water to travel from the water plant to your house, how much chlorine is initially added, etc.

This means that if my tap water contains 0.200 mg/l of chlorine (which is the minimum), and I do a 20% water change in my tank (250l), I would (after the waterchange) end up with a concentration in my tank of 0.04 ppm or 40 ppb, which is more than enough to at least cause some serious stress amongst my fish, not to mention the effect it will have on my bacterialocial population.

So, for all interested, also the new people of course , unless you're using some kind of non-chlorinated well water, rainwater or RO water, don't take any risk, ALWAYS add dechlorinater. It isn't that expensive and it really isn't the product you'll want to save some money on cause you'll risk loosing some fish, if not this waterchange, then maybe next time ...

 

[ScottoMacD]

My first question to you would be. What size is your tank?

The reasoning is. A bigger tank would be able to handle the water change without adding the dechloranator right away.

IE: My bigger tanks. The 77, 55, 50 , and 33. I use a python to clean them.

I always add the water back into the tank, then add my Aquaplus to the water after.

My smaller tanks (3.5, 10, 20) however I use a regular syphon and a bucket. I add the dechloranator right into the bucket of new water with an extra dose before putting it into the tank.

I basically do this because of the volume difference. A 20% water change on a 10 gallon is one helluva lot more potent than a 20% water change on a 77 gallon.

Which means that the smaller tanks have a high risk of having problems develop because of the smaller volume of water that is left in the tank before the new water is put in.

Sometimes on the bigger tanks I don't even add any.

Hope this answers your question.

 

[kvr]

My tank is 65g and using the bucket method on such a tank can be quite a bit of work, I agree. If I would own a python or a similar system, I think the safest way to perform a water change is to add the amount of dechlorinator before you start adding the water again, but you should be safe by adding the required dose afterwards as well. These dechlorinating products work very fast and it should also be ok to add them after the water is changed.

 

[ScottoMacD]

With a 65 gallon I wouldn't worry too much about the chloramine.

Unless you are doing a massive water change 70% + .
Or if you find that the levels are just ridiculously high in your area.

I notice here in Montreal that the levels get much higher in the winter. To the point where there is a faint smell to the water. As oppose to the summer when it is less obvious.

It shouldn't cause you any problems either way.

 

[kvr]

Just as some background information, I always add dechlorinator and as such, I'm not worried about chlorine or chloramine. The reason I put up this tread here (on the new boards) is to continue a tread of yesterday on the old boards, where Faramir asked for some scientific background as a ground for discussion wether or not the use of dechlorinators was needed or not.

 

[ScottoMacD]

No problem..

I didn't see yesterday's thread.

Again though the advice that I gave still stands for that thread also.

 

[RTR]

I'm confused by the idea that the same percentage change has differnt end concentrations in small versus large tanks. A 25% change in a large tank and a 25% change in a small tank should give exactly the same final concentrations of added material in both tanks.

I disagree with the concept.

 

[ScottoMacD]

Originally posted by RTR
I'm confused by the idea that the same percentage change has differnt end concentrations in small versus large tanks. A 25% change in a large tank and a 25% change in a small tank should give exactly the same final concentrations of added material in both tanks.

Robert.
I understand what you are saying.

Reading my posts over I see that my wording is wrong.

I shouldn't have used the word percentage. Gallons would have been a better word.

IE: If you have a 10 gallon and change 5 gallons of it. The cholrine % will be higher when put into the tank untreated, than if you change 5 or 10 gallons in a 33 gallon or a 50 gallon.

Because of the volume differnces a larger tank will be able to dilute the new water better than a smaller tank would making the cholorine/amine less potent as it is mixed in with the established tank water.

 

[kvr]

I agree with you, ScottoMacD, that when you say that, if you change small volumes of water in a large tank, the substances will be so diluted that there effect will be negligible (eg if you change two gallons in your 70g tank every other day or so). But I wouldn't take the risk of chlorine/chloramine poisoning my fish. If I read that even very small amounts of these chemical compounds already causes stress, I would add de-chlorinator every time, no matter how small my water change.

Companies try to sell us a lot of stuff, saying we need it in order to be "good" fishkeepers, that aren't worth one cent, but I would not put dechlorinating agents among those (I'm not saying you implied that )

 

[Rocketman]

Do what I do- I ave no sceduale for water changes, bu I typically do two 25%'s on my 45 each week. And I just add dechlorinator to the tank once a week. Why not? It's much easier.