Are Water Changes Actually Necessary?

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Do you change your water?

  • No

    Votes: 3 0.7%
  • Not unless conditions require it (like high nitrates)

    Votes: 60 13.8%
  • Yes, I do it on a specific timeline (daily, weekly, whatever)

    Votes: 358 82.3%
  • Undecided / Other

    Votes: 14 3.2%

  • Total voters
    435
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kazvorpal

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Jan 22, 2010
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I just engaged in a wordy debate with a few guys who were insisting that frequent, regular water changes are absolutely necessary...yet could not explain why.

They could not give any specifics on what was being altered by the water change, that could not be done in some other fashion.

There was some vague talk of "replenishing and renewing" and "electrolytes", but of course you don't "replenish" anything with a generic water change. The only thing you're guaranteed to be adding is H2O, which does not age...and "electrolytes" sounds like a question of specific gravity, to be taken care of with sea salt.

The actual reason people used to change water regularly was that they were killing their fish with poorly-managed Under-Gravel Filters, and were fighting the nitrate buildup they were causing.

But that's no longer the case, thanks to deep sand beds, open-celled ceramic foam, planted tanks, et cetera. There are many ways to remove nitrates so efficiently that they can become TOO low.

So what reason is left?

What is the reason to do a water change?

And I mean some measurable, explainable reason. Something you can choose to do under specific conditions. Giving a timespan for doing them without reason is meaningless.

Since water changes place stress on fish and ecosystem, by altering the tank's self-imposed balance of micro-organism density, reducing the amount of nutrients, et cetera, water changes were never anything better than a necessary evil.

Are they STILL a necessary evil, and if so, why?
 

Fishfriend1

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Dec 11, 2009
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Mr. Palmer
to add on to what kaz said the water on earth has been reused for about 3 billion years or more. There is no such thing as a global water change. As long as the nutrients necessary for life are there then u do not need to do a wc.
 

Fishfriend1

Fishlover Extraordinaire
Dec 11, 2009
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Mr. Palmer
i found a quote to describe this problem : "You have your way. I have my way. As for the right way, the correct way, and the only way, it does not exist." - Friedrich Nietzsche
 

snoopy65

I am Sam aka Snoopy65
Aug 24, 2008
4,628
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Where the ducks walk on the fish, PA
to add on to what kaz said the water on earth has been reused for about 3 billion years or more. There is no such thing as a global water change. As long as the nutrients necessary for life are there then u do not need to do a wc.
Unless you have the ability to do everything that Mother Earth does, you need to change water. I can not give you all of the minute ingredients in water that the fish use as I am not a scientist. I can tell you this, however, if you don't change water for a long period of time and then you change a bunch......fish die. That in itself tells me that the water changes, loses elements, and gains elements. The idea of water changes is to be able to maintain a steadiness of water quality. Adding salt, whether it is sea salt, iodized salt, or any other kind of salt can not add everything that is needed and it surely does not remove waste. This would be the same as saying you could live in an out house forever with the door closed and the stench and filth would not be there and you would remain healthy so long as you had some salt.
 

msjinkzd

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Feb 11, 2007
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I do water changes because of the need to remove TDS which i do not have a way to measure. This is just from a quick wiki search:

Total Dissolved solids

High TDS levels generally indicate hard water, which can cause scale buildup in pipes, valves, and filters, reducing performance and adding to system maintenance costs. These effects can be seen in aquariums, spas, swimming pools, and reverse osmosis water treatment systems. Typically, in these applications, total dissolved solids are tested frequently, and filtration membranes are checked in order to prevent adverse effects.
In the case of hydroponics and aquaculture, TDS is often monitored in order to create a water quality environment favorable for organism productivity. For freshwater oysters, trouts, and other high value seafood, highest productivity and economic returns are achieved by mimicking the TDS and pH levels of each species' native environment. For hydroponic uses, total dissolved solids is considered one of the best indices of nutrient availability for the aquatic plants being grown.
Because the threshold of acceptable aesthetic criteria for human drinking water is 100 mg/l, there is no general concern for odor, taste, and color at a level much lower than is required for harm. A number of studies have been conducted and indicate various species' reactions range from intolerance to outright toxicity due to elevated TDS. The numerical results must be interpreted cautiously, as true toxicity outcomes will relate to specific chemical constituents. Nevertheless, some numerical information is a useful guide to the nature of risks in exposing aquatic organisms or terrestrial animals to high TDS levels. Most aquatic ecosystems involving mixed fish fauna can tolerate TDS levels of 1000 mg/l.[4]


Daphnia magna with eggs


The Flathead minnow (Pimephales promelas), for example, realizes an LD50 concentration of 5600 ppm based upon a 96 hour exposure. LD50 is the concentration required to produce a lethal effect on 50 percent of the exposed population. Daphnia magna, a good example of a primary member of the food chain, is a small planktonic crustacean, about five millimeters in length, having an LD50 of about 10,000 ppm TDS for a 96 hour exposure.[5]
Spawning fishes and juveniles appear to be more sensitive to high TDS levels. For example, it was found that concentrations of 350 mg/l TDS reduced spawning of Striped bass (Morone saxatilis) in the San Francisco Bay-Delta region, and that concentrations below 200 mg/l promoted even healthier spawning conditions.[6] In the Truckee River, the Environmental Protection Agency (EPA) found that juvenile Lahontan cutthroat trout were subject to higher mortality when exposed to thermal pollution stress combined with high total dissolved solids concentrations
 

kazvorpal

AC Members
Jan 22, 2010
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So far, four people have voted that they do water changes on a timeline...

But nobody has posted any explanation as to why.

This sounds, to me, like people are stressing their fish needlessly.

If not, then we need to hear the actual reason for it.

If someone finds that their nitrates build up, in a shallow gravel tank, with such regularity that they can reliably change the water each week, and they don't care to try some better means of reducing nitrates...that at least makes sense. But, really, it falls into the category of "only change when conditions require", because they took the time and effort to learn the schedule of those conditions, in their specific tank.

People who simply change the water every day/week, because someone told them to...is that doing anything but giving the fish needless stress?
 

Fishfriend1

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Dec 11, 2009
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I top the tanks off about once every 2 weeks.
 

blue2fyre

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Oct 7, 2008
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I do a 75% water change weekly on my 55 gallon. My fish love it and often spawn shortly after. I doubt they are stressed by it. I use to do a 25% water change weekly since I just had a bucket. Once I started doing larger changes my fish were happier and the tank just looked cleaner. My fish grow faster and are generally healthy when I do larger water changes regularly. So I must be doing something right.

I've even had fish heal from disease using large daily water changes alone.
 

kazvorpal

AC Members
Jan 22, 2010
49
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I do water changes because of the need to remove TDS which i do not have a way to measure.
Testing water hardness is pretty easy. There are also TDS meters, you can find some here.

On the other hand, surely if your tank water is hard, your tap water is hard. Or are you concerned that your mildly hard water is accumulating into very hard water, via evaporation and replacement, or that other kinds of organic dissolved solids are doing the same?

If so, how often do you do a change?

You know, I may actually buy one of those meters, if convinced that this is a serious health factor for my fish.
 
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