# Daily or every other day water change?



## talontsiawd (Oct 19, 2008)

I know opinions on water changing differ considerably among people. Right now i'm doing 50% once a week. It has worked out great, I am new, haven't lost any fish, did not do a fishless cycle (i didn't now), and got fish to early (i believe), again, i didn't know.

So at 50%, things seem to be fine, i do not have a test kit, i get my water checked now and things seem fine.

For some background, i just started using Florish as my only fertilizer. My fish are 8 neon tetras, 3 flame tetras, 4 red eye tetras. Size-29 gallon.

The reason i ask if daily is better, or just more, smaller changes are better is it is actually easier for me. My tank is too high to syphon in water so i have to pour it. Doing smaller ones just means less work more often. So as far as an "inconvience" factor, don't take that into account, it's the opposite. I just want to not over do it.

Also note, right now, my tank is still cycling.


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## plantbrain (Dec 15, 2003)

sort of depends on the light itensity, CO2 or not, rate of growth, species kept, load for the tank, state of plant growth/health/density etc.

You cannot broadly define this one without making some specifics known.

You may use test kits to address whether or not you need to do the water change, and chose that.

I do water changes for a few simple, practical reasons.
Trimming/pruning/cleaning is much easier, I like my tanks to look clean, I keep more fish than many might and no testing for nutrients is needed. It's quick and painless.

In lower growth tanks with low light, you can go months with neglect and no water changes. 

So the answer is.........it depends.

Regards, 
Tom Barr


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## die2win (Aug 10, 2008)

*Water changes*

Small daily water changes are fine. :thumbsup: The whole point to changing the water is to reduce the total dissolved solids, (TDS) from getting too high. High would be around 400parts per million (PPM) and can be checked with an inexpensive, (less than $25.00) TDS water test meter. 

I do two water changes a week and then only 10 percent at each change. Depending how many fish and plants you have and the fertilizer loads you are adding will define how much water you should change each week total. :fish:

Your tank will continue to cycle unless you reduce the water changes. Be careful to monitor the ammonia levels and maybe throw in some fast growing plants that will use the pollutants so your fish aren't harmed as the tank cycling catches up


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## talontsiawd (Oct 19, 2008)

Well, for plants, i wouldn't say it's densely planted at all. I have about 8 plants in a 29 gallon of various sizes. I say 8 as many were bunched plants i have sperated. All seem healthy.

I can't comment on the rate of growth as the tank is newer/i don't have any experience.

I'm using DIY co2 with no drop check so i can't say what is really being difussed.

I should get a test kit but my budget is basically nothing right now. It is my next purchase though.


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## die2win (Aug 10, 2008)

Basic test kit or ph/ammonia/hardness etc, is handy and it'll keep you up nights worrying about stuff. 

How do you know that the tank is still cycling?


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## talontsiawd (Oct 19, 2008)

die2win said:


> Basic test kit or ph/ammonia/hardness etc, is handy and it'll keep you up nights worrying about stuff.
> 
> How do you know that the tank is still cycling?


It's a guess but i added 8 neon tetra's 6 days ago.

Test kit is my next purchase though, just waiting to get paid (i'm on a fulltime student/part time low paying job budget).


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## fishscale (May 29, 2007)

One of my oldest tanks hasn't had a water change since December. I just keep topping it off. Duckweed takes care of the cleaning.


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## plantbrain (Dec 15, 2003)

I've had non CO2 planted tanks for over 2 years without a water change, I guess the TDS does not apply there huh?



Regards, 
Tom Barr


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## BradH (May 15, 2008)

plantbrain said:


> I've had non CO2 planted tanks for over 2 years without a water change, I guess the TDS does not apply there huh?
> 
> 
> 
> ...


Wow! May ask what your stock was like in there? That's amazing!


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## itzjustjeff (Apr 27, 2009)

So i wanted to bring this thread back to life hoping to get more incite on the topic..and to address the Benefits/Drawbacks to daily water changes. I know that you Discus breeders do daily water changes to ensure that they get the cleanest water they can, but what about everyone else? I was thinking the Drawbacks would be of course the time spent into the water changes, the extra dosing and water preparation materials required to ensure that the water is ideal for the conditions of your tank, and, lastly, the co2 levels fluctuating. 

What about the benefits? would plant growth substantially rise? Algae propagation substantially drop? Thanks for taking the time to read


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## EdTheEdge (Jan 25, 2007)

I have gone this route.... In an established tank IME it makes it more difficult to dose correctly. I found it unnecessisary in the long run. Although the plants and fish did seem to enjoy the daily influx of fresh water but it was tedious and time consuming. Nowadays I will sometimes do a mid week 25% change in addition to my weekly 50% change and that works really well.

In a new densly planted tank I would just do 3 deep changes a week max. And only for a month. I haven't setup a bare tank in a long long time. You might need to do more water changes with less plants.


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## lauraleellbp (Feb 3, 2008)

I do water changes once every 2-4 weeks on my tanks. 25-50%

They're all low light/low tech and not overstocked, though. Water changes can be detrimental to plants if you're not dosing ferts, which I don't.

Depends on your tank setup and goals.


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## talontsiawd (Oct 19, 2008)

It is sort of funny comming back to this as I do a 1/3 water change every two weeks now. Sometimes less on my 10 gallon. I have less issues overall with both algae and fish. I think 50% stressed my fish since my tank is so much more densely planted. They really didn't have anywhere to go. That is outside of the WC stress. I would start to loose a fish ever few WC before. They just looked scared everytime I put the gravel vaccum in the tank. Anyway, I haven't noticed any negatives of changing the water less often and a lesser amount, only positive. I do run a UV sterilzer on my 29 gallon, nothing on my 10, my 10 gallon will often go even longer and lower % water changes.


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## hydrophyte (Mar 1, 2009)

There was an article on this in TFH from a month or two ago that included calculations comparing small daily vs. larger weekly water changes.


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## Frogmanx82 (Dec 8, 2009)

I think it comes down to how much nitrates you're building up. In a balanced tank, 10% per week would be plenty. I have a low light guppy, shrimp tank that pretty much stays non detect on nitrates. I do 10% per month.

I have about 30 guppies (not counting all the babies), 15 shrimp, unknown number of snails in a 55 dominated by crypts and java moss.


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## NJAquaBarren (Sep 16, 2009)

The TFH article concluded that large watar changes were better at diluting pollutants than more frequent smaller changes. Larger changes remove and freshen a larger % of water. Changing small amounts no matter how frequently doesn't net the same degree of refresh.

If your parameters permit, yould be better off doing less frequent large changes than frequent small changes.

Look up those articles - 2 parts. They were well done.

AB


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## Frogmanx82 (Dec 8, 2009)

NJAquaBarren said:


> The TFH article concluded that large watar changes were better at diluting pollutants than more frequent smaller changes. Larger changes remove and freshen a larger % of water. Changing small amounts no matter how frequently doesn't net the same degree of refresh.
> 
> If your parameters permit, yould be better off doing less frequent large changes than frequent small changes.
> 
> ...


I disagree, changing small amounts add up to a large change. While changing 25% at once removes more pollutants than five 5% changes, five 6% changes removes more than one 25% change. 

With smaller changes you have less stress on the fish and you make each change an easier job. If you have a habit of doing frequent changes and you're happy with it, there is no reason to change. The best systems use a constant drip for water change..

Actually, what's more important than changing the water, is testing the water. Why would you need such large changes in the first place? Depending on the balance of the system, water changes may or may not need to be that frequent.


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## lauraleellbp (Feb 3, 2008)

Frogmanx82 said:


> I disagree, changing small amounts add up to a large change. While changing 25% at once removes more pollutants than five 5% changes, five 6% changes removes more than one 25% change.
> 
> With smaller changes you have less stress on the fish and you make each change an easier job. If you have a habit of doing frequent changes and you're happy with it, there is no reason to change. The best systems use a constant drip for water change..
> 
> Actually, what's more important than changing the water, is testing the water. Why would you need such large changes in the first place? Depending on the balance of the system, water changes may or may not need to be that frequent.


Actually, the math isn't quite that simple.

Say you have 100ppm nitrates in a tank. 

Change 50% of the water on one day, you reduce them to 50ppm.

Change 25% one day, leaving 75ppm, and 25% the next day, you have 56.25ppm instead of 50ppm. Keep going down the line, and you'll see quickly that 3x 25% water changes cleans the water even less in comparison to one 75% water change, and so on and so forth.

When you also start factoring in that nitrates are adding up on a daily basis, the smaller water changes may not even in fact be reducing the overall accrual of nitrates in the tank.

The reason that smaller water changes are "safer" on tanks is the risk of water parameter swings. If a tank is faithfully maintained with larger water changes (given a stable water source), then the fish should have good, stable water in the tank to begin with- and even a 100% water change shouldn't do them anything but good b/c the tank water hasn't had time to shift in parameters from the source water.

It's only when tanks have NOT been maintained with frequent water changes that large water changes are an issue.

It's not an issue on a high tech tank using EI dosing, since 50% water changs are the norm.

On a low tech tank, it's a bit more of a balancing act between the fish's needs for clean water and the plants needs for nutrients. It's very possible to find a happy medium- you just have to take into account what you're working with and pay attention to your tanks! roud:


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## Frogmanx82 (Dec 8, 2009)

First, water changes on the scale of 50% unless you have a nano tank is excessive. I only do water changes at 10% every other week or so and still have nitrates less than 5 ppm. A 100% water change would not be good and only an option of last resort for dying fish. You have a lot of posts Laura, but I think your advice is a bit off.

"When you also start factoring in that nitrates are adding up on a daily basis, the smaller water changes may not even in fact be reducing the overall accrual of nitrates in the tank."

I'll say it again, test first, then decide how much water change you need to do. And while smaller frequent changes will need more water than a single large change for the same effect, telling people that frequent smaller changes are ineffective is just wrong. If your nitrates are accumulating faster than a daily 5% water change can handle, you need to be doing something else with the tank.


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## lauraleellbp (Feb 3, 2008)

Again, it depends on your setup and goals. I disagree 100% with your blanket statement that 50% water changes are excessive.

If you're raising juvenile fish- take for example, juvenile discus, breeders in Asia tend to do *multiple 100% daily* changes and it clearly maximizes their growth and coloration.

You have an African cichlid tank that's fully stocked and overcrowded to minimize their aggression, weekly 50% water changes are usually also a good idea since the tank has such a high bioload and cichlids are such messy eaters and waste factories.

You have a 100gal fully planted tank with a school of 20 tetras and nothing else in the tank, of course routine large water changes aren't necessary.

It's also possible to maintain a tank without ANY water changes (Diana Walstad popularized her Natural Planted Tank method).

Nitrates are a good indicator of when water changes are needed, but there are plenty of other waste products/toxins (hormones, oils, etc) that we don't test for that also can build up and may not necessarily be taken in by plants. Water changes are the only way to remove these, and a 50% water change only removes 50% of them... so yet another reason that large water changes can be beneficial. To use discus as an example again, large adult discus secrete a hormone that can stunt the growth of other smaller discus in the tank (it's a competition/survival strategy). Big water changes can help prevent the smaller discus from being stunted. This issue has nothing to do with nitrate buildup.

If you want to talk ONLY about fish health, the more water is changed in a closed system, more frequently, there is plenty of documentation to show that this is what promotes the best fish growth, color, & health. 

When you add plants into the equation, it becomes a bit more of a balancing act.


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## lauraleellbp (Feb 3, 2008)

Oh another issue as well-

It's usually a wise decision to try and maintain your tank water parameters to match your source water parameters as closely as possible. This not only reduces acclimation stress on fish during routine water changes, but also means that in case of emergency you are not scrambling for suitable water.

Due to evaporation, biological activity (organic buildup & decomp), etc it is natural for a tank's water parameters to shift over time. The easiest way to ensure that a tank's parameters remain in line with those of source water (tap, RO, RO mix, etc) is through frequent water changes.

10% every other week or so where I live (south florida) would not be enough to remove the TDS that are left behind by evaporation in my tanks. Doing a 10% water change doesn't dilute TDS concentrations very much, and the water in the tank would end up getting harder and harder... If I only ever changed 10% of my water at a time, over the years (and I love setting up tanks and leaving them running for as long as possible) I'd end up with an extreme difference in the TDS in my tanks versus my tap water. And THOSE types of differences can kill fish during water changes, especially if I then went and did a large one.


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## EdTheEdge (Jan 25, 2007)

Thanks Laura Lee! Well said! roud:


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## hbosman (Oct 5, 2006)

For years I thought 50 % water changes would be excessive, given my fish population. But one day, I just got tired of playing with highly inaccurate Nitrate test kits. And, after reading how to calibrate a test kit, I thought maybe Tom Barr's idea of 50 % water changes and EI might be easier after all. I went to 50 % water changes from 33 % water changes and still saw a dramatic reduction in GDA and BBA. I think a 50 % water change is less time consuming than doing a 25 % water change and testing every other day. I don't have to buy the test kits and Seachem Excel (for fighting algae) any longer.

I should have paid attention years ago. And yeah the TFH article explains the math why 1-50 % is better than 2-25 % water changes.


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## NJAquaBarren (Sep 16, 2009)

LauraLee is spot on.


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## Frogmanx82 (Dec 8, 2009)

There is nothing wrong with frequent small water changes as it keeps the water quality more constant. While big water changes help get drastic reductions, you also tend to have big swings in water quality which isn't great either and as Laura said can harm fish if the swing is really large. 

That being the case, I don't know why you would advocate a 50% change over two 30% changes. More frequent smaller water changes are better for the fish. If 30% once a week isn't cutting it, doing two 30% changes in a week is better than a 50% change. If you won't do water changes that frequently, then a 50% change that keeps nitrates in check is of course better than a 30% weekly change that doesn't. 

I have a big african cichlid tank that I do weekly 25% -30% water changes on. This being a planted tank forum, I would have expected tanks to be a bit more balanced and not need that much water change. 

Weekly testing of nitrates, hardness and pH will let you know how much water change is necessary to maintain water quality and 5% per week would be a minimum even for a well balanced tank. 

If we agree to disagree, no problem. Sorry if I set too harsh a tone.


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## lauraleellbp (Feb 3, 2008)

I think what you're missing is that many people on here maintain high tech planted tanks and follow the EI fertilizer dosing system.

EI dosing was developed by Tom Barr for people who don't want to be testing constantly to monitor and maintain specific nutrient ratios- instead, you supply an overabundance of ferts in the water column and the 50% weekly water changes helps "reset" the tank and keep those ferts from building up to excess. 

It's a fairly user-friendly fertilizer dosing regimen, as you just do your water change, dose your ferts, and you're good till the next week.

As I mentioned earlier, I keep low tech tanks and I DON'T do weekly water changes on my own tanks, either. :biggrin:


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## Frogmanx82 (Dec 8, 2009)

I've been keeping fish for 35 years but have to admit the high tech planted tank is something I'm not familiar with. I have a low tech planted tank which needs minimal attention which is good since my 90 gallon mixed reef tank requires lots of testing and care.

I guess it just comes down to what type of tank you have and what your habits are for maintaining it. I wouldn't think a high tech planted tank would have nitrate issues but I hadn't considered the ferts.

I'm interested in picking up some good advice on planted tanks here and perhaps I'll venture into the high tech arena at some point.

For the moment I am thinking of going with some flourish excel, but that's a topic for another thread.


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## hbosman (Oct 5, 2006)

Another thing that I like about 50 % water changes. My tank is about 21 inches high so when I stick my arms in the tank for cleaning, water tends to drip off my elbows onto the sides of the tank. If I remove 50 % of the water first, my elbows are above the water line. :biggrin:

If I didn't do the water changes weekly, the water quality change would probably be unhealthy for the fish.


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## lauraleellbp (Feb 3, 2008)

Frogmanx82 said:


> I guess it just comes down to what type of tank you have and what your habits are for maintaining it. I wouldn't think a high tech planted tank would have nitrate issues but I hadn't considered the ferts.


Now we're in 100% agreement. :biggrin:

And it's not just the nitrates to take into account- you've got phosphates, potassium, and whole host of micros... dosing phosphates into a tank on purpose may be a bit of a mind-warp for ya too, if you're used to keeping reef tanks. :hihi:


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## lauraleellbp (Feb 3, 2008)

hbosman said:


> Another thing that I like about 50 % water changes. My tank is about 21 inches high so when I stick my arms in the tank for cleaning, water tends to drip off my elbows onto the sides of the tank. If I remove 50 % of the water first, my elbows are above the water line. :biggrin:
> 
> If I didn't do the water changes weekly, the water quality change would probably be unhealthy for the fish.


So you mean your fish don't like deodorant? :hihi:


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