# Water changes- how often?



## discuspaul (Jul 27, 2010)

IMO & E., for properly maintaining any planted tank, and ensuring healthy & thriving fish, generally speaking the more frequent, and larger the water changes, the better. Primarily prevents the development of unhealthy conditions due to accumulation of wastes in these limited spaces, and replenishes needed mineral content for the benefit of livestock & plants. Smaller tanks, say under 100 gallons, will do well from receiving weekly wcs of 50% or more.
Many may argue that far less frequent wcs will suffice in a well-kept, balanced aquarium environment, but that is seldom the case in our busy lives, so the infusion of fresh new water will be always be a much acceptable mitigating approach. 
It has also been shown many times over, that the higher the bio-load, the more reason there is to accelerate the frequency & quantity of wcs.
That's my .02 cents.


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## latchdan (Sep 7, 2007)

High tech 50% weekly, low tech shrimp 15% every other week.


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## cobra (Feb 4, 2005)

Hi tek, low light, 50% change every 7-10 days.

Cheers,
G


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## megatrev62 (Sep 26, 2014)

Thanks alot. I was thinking of 50 % at least every 10 days. I'll give that regimen a go.


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## Remmy (Jan 10, 2007)

High tech medium light, low bioload. When the glass starts turning green, so 3-4 weeks 50%. Works for me


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## sohankpatel (Jul 10, 2015)

60% every sunday, no exceptions. Just what I do.


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## roadmaster (Nov 5, 2009)

+one^
Makes no matter,is same for year's.


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## Warhawk (Feb 18, 2016)

I do 25% water change every week on my lightly stocked tanks, my tanks with fry I do two 25% water changes a week.


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## Nordic (Nov 11, 2003)

40% weekly regardless of lighting.... had a nasty experience with a 50% change where the silicone at the top of the tank gave way... so now I'm superstitious about 50.


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## nel (Jan 23, 2016)

Medium tech, every week 10%, but this tank is going without restart for 6 years, so I know it well. On the other hand, in my outgrow tank I'm doing 2-3 25% water changes every week.
Edit: it's good to start even with 50% and later on try smaller and smaller water changes.


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## Edward (Apr 11, 2005)

If more water changes is better than why changing 90% tap water daily makes plants sick?


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## Straight shooter (Nov 26, 2015)

Edward said:


> If more water changes is better than why changing 90% tap water daily makes plants sick?


CO2 fluctuations
Big Temp changes 
Removal of beneficial nutrients


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## roadmaster (Nov 5, 2009)

ADA Aquasoil user's change lot's of water initially, with no harm to plant's. NO?
Who changes 90% daily?


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## Hoppy (Dec 24, 2005)

I have done changes from 10% to 90% and have yet to see any harm to fish or plants that could be attributed to the water changes. Right now I am on a 50% every 2 weeks schedule, with a non-CO2, low medium light tank, with medium planting density and low fish load. I chose this because of my low NPK dosing, allowing me to not worry about build-up in NPK in one week.

Bump:


Edward said:


> If more water changes is better than why *changing 90% tap water daily makes plants sick?*


Is this something you have seen consistently? Or, just once, or just as reported by someone, or as reported by several others? I haven't heard this before.


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## Edward (Apr 11, 2005)

roadmaster said:


> ADA Aquasoil user's change lot's of water initially, with no harm to plant's. NO?
> Who changes 90% daily?


 Sure, because tap water is a lesser evil than the ammonia released from new Aquasoil. But again, try changing 90% tap water every day on mature planted aquarium and tell us how it goes. All in support of the notion that more water changes is better for planted aquariums. If you prove it to be favorable then you are very lucky to have such a water source. Most tap waters differ.


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## CrypticLifeStyle (Jan 16, 2013)

You can figure out how much, and how often based on your average water readings. 25%-50% is the norm, but not necessarily necessary.
Every tank has it's own unique needs.


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## Edward (Apr 11, 2005)

Straight shooter said:


> CO2 fluctuations
> Big Temp changes
> Removal of beneficial nutrients


 Are you saying tap water changes are not harmless?


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## roadmaster (Nov 5, 2009)

Edward said:


> Sure, because tap water is a lesser evil than the ammonia released from new Aquasoil. But again, try changing 90% tap water every day on mature planted aquarium and tell us how it goes. All in support of the notion that more water changes is better for planted aquariums. If you prove it to be favorable then you are very lucky to have such a water source. Most tap waters differ.


 
Repeat,,who changes 90 % daily?
Three weekly water changes of 50% was most I have ever done, and that was while raising some young Discus.
I had no plant's, but fishes grew to adult size in less than eight month's.


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## aja31 (May 25, 2013)

It can depend on your fish as well. If you have small discus in the tank then you'll need to do at least 25% daily to prevent stunting. If you have fully grown discus you'll want to do at least 50% a week, preferably splitting it into multiple changes. 

If you overfeed you should change water more often

The less plants you have the more water you should change since less of the stuff in the water gets used by the plants.

Every tank is different, there isn't really one set answer.


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## Edward (Apr 11, 2005)

Hoppy said:


> Is this something you have seen consistently? Or, just once, or just as reported by someone, or as reported by several others? I haven't heard this before.


 More tap water I change worse results I get in terms of plant health.
Also, there are many posts on many forums about more tap water changes performed being linked to detrimental plant health. 

Very few people tried to grow plants in fresh tap water but still claim its success.


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## houseofcards (Mar 21, 2009)

Edward said:


> If more water changes is better than why changing 90% tap water daily makes plants sick?


Edward I see where your going with this, but let's be honest this is not something anyone would do or would be required to do in planted aquaria. If for some reason I had to do this to maintain a setup I would have left the hobby a long time ago.

Everything has ranges in this hobby (temp, co2, light). Putting a statement out that 90% daily water changes make plants sick is just out of any range in the context of the hobby. How is it applicable unless you just like to test things?

I'm pretty anal with things and have done 40-60% water changes with low tech to high light/high tech on countless setups and never found any downside to fish or plants.


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## GraphicGr8s (Apr 4, 2011)

If I had my druthers I would be changing 50% in each tank every day. I've just found that in most cases everything does better and fish breed with regularity and with healthier fry. Plants also seem to do very well. But I am on untreated well water.


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## Edward (Apr 11, 2005)

roadmaster said:


> Repeat,,who changes 90 % daily?


 Why not change 90% daily when most posts are recommending water changes and more water changes in order to have healthy plants. My answer is that more is not necessarily better and people should try it before posting such claims.

Bump:


aja31 said:


> If you overfeed you should change water more often. The less plants you have the more water you should change since less of the stuff in the water gets used by the plants.


 +1


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## roadmaster (Nov 5, 2009)

I fear unlike houseofcard's, that I do not see where this is going.
I know of no one who does 90 % daily water changes with tap water or any other kind of water (cept maybe some Discus purist's), nor have I read anywhere where this was suggested.
Please tell me there isn't a tap water toxicity thread about to jump off.


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## jw.cS (Jan 13, 2005)

Edward said:


> Why not change 90% daily when most posts are recommending water changes and more water changes in order to have healthy plants. My answer is that more is not necessarily better and people should try it before posting such claims.


Mr. Edwards. Out of curiosity, why are large frequent water changes in a mature tank detrimental? Is it something beyond just the typical macro/micronutrients?


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## Edward (Apr 11, 2005)

houseofcards said:


> Putting a statement out that 90% daily water changes make plants sick is just out of any range in the context of the hobby.


 I like your response except I didn’t say it that way. You are missing the key word of my argument “*tap*”.


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## CrypticLifeStyle (Jan 16, 2013)

Higher percentage of water changes maybe be better for plants, but are they for fish with the constant fluctuations, i say not likely. 
Each with it's own requirements, and preferred environments.


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## houseofcards (Mar 21, 2009)

Edward said:


> I like your response except I didn’t say it that way. You are missing the key word of my argument “*tap*”.


For the sake of accuracy, yes, your right I did leave out the word tap (not on purpose) and I know you feel that makes a large difference and it might at 90% daily. I certainly couldn't tell you since I'll repeat what I said in my earlier, post. I don't think 90% daily TAP water changes are applicable to the hobby. If that's your response to someone saying that the more water changes the better I don't think it carries much weight, since it's understood on the boards that your not changing 90% daily. Just like it's understood that high light isn't putting your tank on a sun porch.


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## jr125 (Mar 5, 2015)

If everybody had the exact same water coming out of their tap you could make generalized statements about what the results of doing water changes with that tap water are. Since everybody's is different the results they get are uniquely their own.


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## Empress Akitla (Nov 17, 2011)

I do 25% water changes on my 29 gallon every Sunday and 40% water changes in my smaller tanks. All my plants seem to be doing well.


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## jw.cS (Jan 13, 2005)

houseofcards said:


> since it's understood on the boards that your not changing 90% daily. Just like it's understood that high light isn't putting your tank on a sun porch.


For argument's sake, let's assume that I make 90% daily tap water changes. Why is this so bad? Is there something beyond just the micro/macronutrients? If I were to reconstitute with all the C, N, P, K, etc., then is it okay?


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## SwissCheeseHead (Dec 24, 2014)

Edward, I think you're making s HUGE mountain out of a mole hill. Your statement of 90% water changes daily is completely out of left field. It seems that you are arguing for argument's sake. The statement which I believe you are referring to of "the more frequent water changes, the better" or something to that effect, is totally taken out of context.

Do you have evidence that 90% water changes daily are detrimental to plant and fish health and growth (assuming everything else is constant, such as CO2, macros/micros, light, fauna?)

Have you done a side by side comparison of tanks that received 90% daily, one that received 50% daily, one that received 25% daily, same for 90%, 50%, 25% weekly and one with no water changes at all, and have documented outcomes of each of the tanks, again with water changes being the only variable? Of course not. 

So what's the point you're trying to make? No one has said "do as many WCs as you can each day or each week and you'll have a great looking tank." All the majority have stated was, doing 25%-50% weekly is a good regiment to get into. I do 40% changes weekly myself. That's the general consensus in the hobby. You can argue all you want, but there's nothing for you to stand on. 

And the last thing I want is for someone to read this thread, see your statement, and NOT get into the hobby because they're afraid that they will have to do this ungodly amount of tank maintenance, that no one has even recommended.

*TL;DR *
90% water changes daily are "whaaaaat?"
25%-50% water changes weekly are the consensus in the hobby.
*mic drop*


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## houseofcards (Mar 21, 2009)

jw.cS said:


> For argument's sake, let's assume that I make 90% daily tap water changes. Why is this so bad? Is there something beyond just the micro/macronutrients? If I were to reconstitute with all the C, N, P, K, etc., then is it okay?


That's my line, LOL. I personally believe all water changes are good for fish/plants as long as your putting the ferts back in, but again I can't account for someone's tap at 90% daily since I've never done it. It's just not applicable other than to experiment outside of the hobby.


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## Edward (Apr 11, 2005)

jw.cS said:


> ... Out of curiosity, why are large frequent water changes in a mature tank detrimental? Is it something beyond just the typical macro/micronutrients?


Thank you for your response, glad you asked. 
This is about plant’s negative reaction to tap water sources in many cities. We know that this has been observed by many but still there are others having no issues what so ever. It is not caused by nutrients we dose because we can compensate for the volume exchanged and still have problems. 

I think there are two reasons behind this. 
One reason is a rapid change in aquarium water parameters caused by new water addition. This applies when infrequent large water changes are performed. The water can be of any source, tap or RO. 

The second reason, having the most negative impact on plant health are the megatons of chemicals being dumped in our drinking tap waters. I will not name the long list of toxins here, from tooth decay fluoridation, industrial pH buffers and pipe anticorrosion compounds and the list goes on, just Google your city utility tap water report and other unofficial analysis sources. This is not good news for plants.


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## jw.cS (Jan 13, 2005)

Sometimes, not everything must have empirical evidence before it can be uttered and discussed. Theoretical work is very important and crucial in cementing "facts" and bringing up new "facts." These kinds of discussion are not geared toward the casual hobbyists. They must wait until these kinds of theoretical work and thought experiments to bear fruits and be distilled down to the everyday experience. So please, I implore everyone to not let yet another extremely interesting conversation devolve. Otherwise, this forum will just be another boring collection of "facts" (is it?) and there is not going to be any platform available for the "intellectuals" to do their thing and this hobby becomes stale as heck. Edward, Marcel et al. pose vexing points and questions our logic. That is some valuable sh$%! So let me pick their brains please! Otherwise, point me to where I can come and be an audience member, listening to the "greats" discuss the frontiers of this hobby and throw shade at age-old idioms and see what stands. Who doesn't like a little drama? Heck, I'd throw shade too if I know what I am talking about. *laughs* Lighten up folks.

Einstein's work is still debated and questions raised even after all these years and all these experiments. Nothing should EVER be taken for granted as the final word. TED talks, Asimov debates and gravitational waves turning anyone on? I am.


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## SwissCheeseHead (Dec 24, 2014)

If intellectual conversations and thought experiments are the intent of Edward's post, then I feel like a new thread should be created for that very purpose. I've gone through what I can with Marcel's thread, but that was started with the intention of garnering responses such as Edward's.

This thread was started with the sole purpose of finding out what other "well established" practices people did, so that he/she, as a new hobbyist, can develop their own routine. Edward could have very easily started a thread of his own "The more the better - is it really?"

Instead, it totally veered the OP's thread off course.

I'm all about theories, thought experiments, and exploring new frontiers. I think there's a proper time and place for it. I don't think a legitimate question should be muddied up by theories.


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## houseofcards (Mar 21, 2009)

Yeah I agree. I mean it doesn't help the OP at all IMO. If no one is doing 90% water changes other than to experiment, it's not applicable. What is applicable is the 10-70% weekly depending on their setups.


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## Burito (Oct 15, 2015)

I'd say tank size plays a role here. IME, in small nano tanks once a week is not enough.


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## discuspaul (Jul 27, 2010)

Hoppy said:


> I have done changes from 10% to 90% and have yet to see any harm to fish or plants that could be attributed to the water changes. Right now I am on a 50% every 2 weeks schedule, with a non-CO2, low medium light tank, with medium planting density and low fish load. I chose this because of my low NPK dosing, allowing me to not worry about build-up in NPK in one week.
> 
> Bump:
> 
> Is this something you have seen consistently? Or, just once, or just as reported by someone, or as reported by several others? I haven't heard this before.



Neither have I.


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## Straight shooter (Nov 26, 2015)

Edward said:


> Are you saying tap water changes are not harmless?


I'm saying that 90% WCs have a bigger negative impact on the balance of the tank than smaller water changes. It's generally not beneficial to perform WCs of this size if a smaller WC will suffice.


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## gbb0330 (Nov 21, 2015)

I do 5% weekly on my 40B, fish and plants are doing great. and about 30% weekly on my 3G shrimp tank.

I often use filtered and boiled rain water instead of tap water.


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## burr740 (Feb 19, 2014)

60-70% every 5-6 days on my high techs, rarely ever go 7 in between, but it's fine if I happen to do it that way.

Any time there's a problem it goes to twice a week. The plants are always happy right after a water change. 100% tap. Guess Im just lucky...


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## mik778866 (Aug 22, 2014)

Ones tank setup should dictate amount and frequency of WC. Some people do twice a year, whilst others once a week. 


Sent from my ALE-L02 using Tapatalk


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## SNAXX (Dec 30, 2015)

Good luck finding a consensus on this one lol. We all have our own regimens based on our experiences. I would say you need to adjust your water changes according to your lifestyle. If you are a busy person with limited time for maintenance I would suggest a lightly stocked heavily planted tank. That way a missed water change or two wouldn't have dire consequences and regular large changes aren't a necessity. If you are able to take the time to keep up with a heavily stocked and planted tank, you would need to do weekly partial water changes between 25-40% depending on your bio-load. I typically do a 50% change once a month. The rest is a 25%-40% basically depending on my gut feeling lol. Doing weekly 50% water changes is excessive, unless you are doing EI dosing.

My own water change percentages have been rising with the stock of my fish. This site has a calculator for aquarium size, filtering equipment and livestock. I think it's on point, check it out.

http://aqadvisor.com/AqAdvisor.php


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## roadmaster (Nov 5, 2009)

I agree that large water changes can be detrimental if few and far between, but if one begins with 50% weekly water changes from the outset, and sticks with it,then tank water will not deviate much from source water unless one is altering the water in some way.
Also agree with water sources becoming more and more sketchy.
Need only look at Flint Michigan for example.(criminal?)


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## Straight shooter (Nov 26, 2015)

Flint MI is likely criminal negligence, will see what the fallout is..


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## Santose2008 (Dec 11, 2015)

I do a 25 percent water change ever Saturday in my low tech heavily planted 55g tank. My tank looks healthy to me. I like to keep myself on a schedule this way, or the water change becomes unbalanced because of my work schedule. It's better to replenish new water every week, then do a big water change down the road that could affect your fish or the environment. But that is just my opinion on my tank.


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## Kubla (Jan 5, 2014)

Edward said:


> I like your response except I didn’t say it that way. You are missing the key word of my argument “*tap*”.




I think you actually have the key word wrong. It should be "Fresh".
I do about a 50% water change every 1-3 weeks. All the water in my tank is "tap" water. I take out aged tap water and replace it with fresh tap water.



> The second reason, having the most negative impact on plant health are the megatons of chemicals being dumped in our drinking tap waters. I will not name the long list of toxins here, from tooth decay fluoridation, industrial pH buffers and pipe anticorrosion compounds and the list goes on, just Google your city utility tap water report and other unofficial analysis sources. This is not good news for plants.


Some of the added chemicals don't evaporate with water. Fluoride is one of them. If you keep adding fresh tap water to your evaporating tank you will slowly increase the amount of fluoride. The only way to counter that is to use another source of water, or do water changes. The bigger and more frequent, the more effective they will be.

And yes, changing all your water everyday with fresh tap water will probably be an issue. Changing it once an hour will cause more issues. There comes a time when common sense needs to take over....


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## AWolf (Jun 13, 2014)

If you have abundant floating plants that are very healthy then you can do few water changes a month. I check for ammonias and nitrates every week, but only add water as it evaporates on low bioload/heavy floating plant tanks. (Just adding water equals to about a 10% new water weekly.) Once a month siphoning crud adds another 20% fresh water. So a total of 60% fresh water monthly.

No floating plants, but heavy 'planted' tanks, heavier bioload, weekly water changes of at least 50% has worked for me. Sometimes less. But still weekly. I also check chemistry every 3-4 days on these tanks. Heavy bioload can make ammonia sneak up quickly, and the plants and/or filters can't keep up.


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## Nordic (Nov 11, 2003)

If you premix your fertiliser into the new water, it would be like repotting every day into fresh soil.... minus the root damage.

I suppose the correct way to go about it would be to top off tank with RO/DI first, _then_ run your water change.

You still end up with the same stuff in the water before the change, but the ppm ratio is back to its original state.


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