# How often and how much water do you change? changes?



## Hawkian (Oct 29, 2009)

OK this one is partly because I am curious and partly for fun. Mostly it is to get an idea of how others maintain their tanks.

I do a 20%-30% water change every week on my 32g freshwater tank, depending on the Nitrates (NO3) reading. I find that this works well for me. However, I often read posts where folks do 40% or even 50% and the frequency also varies between weekly to bi-weekly to monthly. I am not talking about "problem maintenance" but regular maintenance.

So... how big a tank do you have and how much water do you change at which frequency? And why?

:hmm: Guess I screwed up the title there eh?


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## stephanieleah (Oct 31, 2009)

29 gallons

40% wc 1-2 times weekly (twice if there's a lot of fish poo at the bottom!)

I'm glad you posted this thread bc i'm also curious. I was thinking about youtubing myself doing a water change and asking people if they thought i was doing it right


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## WisFish (Dec 16, 2008)

55gal planted tank. 50-60% changed every-other Saturday. With my busy schedule and kids, that's about as frequent as I can get. It's also why I only have 1 tank setup right now.


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## kevincao (Jan 7, 2010)

it depends on the filtration system and your tank size

too much water change can affect biological filter, and may destroy good bacteria colony, and filters should never be thoroughly cleaned, for the bacteria will have to re-colonize. and can have some dramatic changes to your fish. 

i have 220 gallon, and i do water change once few month, because i use sump system, and my sump is 80 gallon so together is 300 gallon of water. but i do change first level filter matt bi-weekly

from the amount of fish you have there in your signature, i would suggest you to have...

15% water change per week
40% - 50% water change per month depended on your monthly food consumption.


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## kevincao (Jan 7, 2010)

stephanieleah said:


> 29 gallons
> 
> 40% wc 1-2 times weekly (twice if there's a lot of fish poo at the bottom!)
> 
> I'm glad you posted this thread bc i'm also curious. I was thinking about youtubing myself doing a water change and asking people if they thought i was doing it right



hi, personally i think you are changing the water too frequent, you should try 30% per week, but i'm not sure how crowed, or heavily planted your aquarium is. so i assume that it is very crowed and so you should do 30%

but really is not all about water change


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## Mikaila31 (Dec 18, 2008)

At least 50% every week.

You can never do too many water changes.;-)


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## iamntbatman (Jan 3, 2008)

Yeah, it really depends on the tank. My smaller ones get about a 50% change once a week while the bigger ones only get about 20%.


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## aunt kymmie (Jun 2, 2008)

My tanks get a 50% water change weekly. (100gl and 2 little 6gls tanks) Once in a while the water change extends out to ten days rather that seven but that's not very often. Tanks are heavily planted, I use ferts for the plants. Based on the behavior of my fish following water changes I'm convinced I'm doing the right thing by them.


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## mrdemin (Oct 4, 2009)

Ahem, I do a 17 % change every Tuesday in my 29g


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## stephanieleah (Oct 31, 2009)

aunt kymmie said:


> My tanks get a 50% water change weekly. (100gl and 2 little 6gls tanks) Once in a while the water change extends out to ten days rather that seven but that's not very often. Tanks are heavily planted, I use ferts for the plants. Based on the behavior of my fish following water changes I'm convinced I'm doing the right thing by them.


For some reason you just made me think about my plant to get a 55 gallon. Currently when I do a 40% wc on my 29 gallon, it only adds up to about 10 gallons of water being changed (my plants and decor take up a lot of space i guess!). So that's basically two five gallon jugs of water, and two five gallon buckets full of waste to dump down the toilet. But if I do a 50% wc on a 55 gallon, that's a whopping 5 bottles and buckets worth of new and waste water. yikes. Can my back handle all of that water???

And by the way I would change more of my water if I could...sometimes I still see floating matter in the water after my wc and I wish i had sucked out more of the old water. 

IMHO...how can one go wrong with clean water? (never seen any problems with my bb...my params are very stable always)


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## jeaninel (Aug 24, 2007)

Tanks are in my sig. 30% weekly water changes except the bettas usually about 50% (their tanks are cycled). SW is about 10-15% every other week.


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## kevincao (Jan 7, 2010)

hmmm, i guess is just me who don't do lot of water change, i'm not sure if is because the tank set up. anyway here is my tank set up


fish i'm housing are, arowana, pacu, tiger oscars, and blood parrots

tank is 220 gallon, with a pump at the very bottom of the tank pumping 3300L/hour (this is not the sump pump)

the sump can hold up to 80 gallon of water (which makes 300 gallon water in total) the sump pump is a mag 18

the tank is "poo less" because the in tank pump (not the sump pump), it picks up the poo and takes it out through the overflow

so all i have to do is change the filter pad every 2 weeks.


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## iamntbatman (Jan 3, 2008)

But, as long as the fish are passing waste, ammonia still builds up in the water (which turns into nitrite and then nitrate). Even with the best filters around and a huge tank you still need to be doing water changes to reduce the nitrate levels. That, and there are trace minerals in water that get depleted over time and need to be replaced.

Do you take regular nitrate readings on your tank?


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## kevincao (Jan 7, 2010)

yep i do, i do changes once is high, which happens in few month. reason being as i've posted above, because i have a pump at bottom of the tank, so any un-eaten food or wastes and such will be picked up and go through the overflow, my tank has no decroations no gravels, nothing bare bottom tank. so for me i don't really need to change water every week


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## Jill0 (Jan 8, 2010)

I _love_ doing water changes!

In most of our tanks, I do 30% once a week, but sometimes twice because I like to (crazy?!?!). However, for our fancy goldfish tanks, I do large 70% or so partial water changes 2x a week.


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## 1077 (Apr 16, 2008)

Change 25 percent twice a week, with 50 percent on weekend for total of 100 percent weekly. If I had live plants that could use some of the excess organics, then perhaps I could /would, cut back.
Fish always appear to enjoy a water changes and I like cleaning the tank and servicing filters. Brings me some serinity.


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## Angel079 (Feb 14, 2007)

Between 30-40% on 55g and 45g About 25-30% on both 10g; all done in one go each weekend.


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## kevincao (Jan 7, 2010)

Jill0 said:


> I _love_ doing water changes!
> 
> In most of our tanks, I do 30% once a week, but sometimes twice because I like to (crazy?!?!). However, for our fancy goldfish tanks, I do large 70% or so partial water changes 2x a week.



wow your tanks are amazing, your water changes sure paid off, when i first saw your 75g i thought it was a 220, cause it looks so much like mine, that's some serious fish keeping there


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## Byron (Mar 7, 2009)

Before I offer some general advice on partial water changes, I must correct some inaccurate comments in previous posts.



> it depends on the filtration system and your tank size


The filter/filtration system has no bearing on the need for partial water changes; no filter or combination of filters can replace the pwc, as I will hopefully explain below. The tank size does have an impact, as will also be seen below.



> too much water change can affect biological filter, and may destroy good bacteria colony, and filters should never be thoroughly cleaned, for the bacteria will have to re-colonize. and can have some dramatic changes to your fish.


A water change will not affect the biological filter, nor the bacteria. Nitrification bacteria live on solid surfaces covered by water, be it the filter media, grains of substrate, plant leaves, tank walls, wood, rocks, decor... whatever; they do not live in water, and the bacteria colony is not affected by changing water. The filter is a different matter, this will obviously impact the bacteria colony if done incorrectly.


> personally i think you are changing the water too frequent, you should try 30% per week, but i'm not sure how crowed, or heavily planted your aquarium is. so i assume that it is very crowed and so you should do 30%


If a tank is actually crowded, a mere 30% pwc once a week will have very little impact. Maybe 30% every day might help... but this will be covered below.

To the partial water change, starting with the reason, which is often stated to be the need to reduce the nitrate levels; this is part of the reason but not the really important part. And at this point I would mention that in planted tanks, nitrates should not be above 10ppm and thus a pwc for nitrate reduction is not relevant--yet the pwc is still critical for most of us with planted aquaria. In non-planted tanks, nitrate levels can rise substantially and the pwc does assist in keeping nitrates low. But even in these tanks, this is not the major reason.

Fish produce waste, solid and liquid--this is pollution; we can usually see some of the solid waste on the substrate and trapped by the filter media before it is broken down by bacteria into liquid or we remove it by vacuuming the substrate and rinsing the filter media. We cannot see the liquid, nor can we see the liquid resulting from the decomposition of the solid. And no filter will remove this. This is why the type of filter, or the number of filters, has no relevance. The liquid waste--pollution--remains in the water until the water is removed.

In a planted tank, the plants do remove this liquid waste, in time; but it takes a long time and a fully-planted tank would handle a very minimal fish load without a pwc. One author suggested 6 or 7 neon tetras in a well-planted 55 gallon aquarium would be the limit for the plants handling the waste. Most of us keep more fish load than this, so we are left with the pwc as the only method of removing the pollution.

Fish produce an amazing volume of pollution. An average tetra can eliminate its body weight in urine alone every 4-5 days. And multiply that by the number of fish and it should be easy to see that our fish are literally swimming in a tank of urine. Not to mention the liquefied solid that is building up as well.

Tank size was mentioned earlier. The larger the aquarium and the fewer the fish, the less pollution will be in the water. So tank size has a bearing on the pwc from this aspect. But here again, most of us stock our tanks far beyond the capacity of the volume, relying on mega fast-flow filters when in fact these do nothing to help the real problem, pollution. Plants significantly help, as mentioned before, plus their ability to act much like carbon in removing toxins and their ability to release oxygen in an amount beyond what the fish and bacteria require. The immense benefit of live plants cannot be understated. But back to the pwc.

It is frequently advocated that less water more often is preferable to more water less often, and the reason is usually given as water stability; but this is now understood as being largely inaccutrate. There is a two-part article in the November and December 2009 issue of TFH that explains the mathematical and scientific reasoning behind doing major water changes at least weekly. Members can dig those articles out for details of the studies. The conclusion is that changing 70% of the water once a week has greater positive effect that changing 10% each day. The larger the pwc, the more polluted water is removed, so the fish are living in less-polluted water for more of the week. Of course, a 50% pwc every day would be even better, and some who raise discus do just that. But for most of us, a weekly schedule is more likely to be adhered to, and that is very important. So, I recommend you increase those minimal water changes weekly. Your fish will thank you. There is ample scientific evidence on the positive effects of significant pwc on fish in an aquarium.

Last note on the water stability issue. Changing large amounts of water in a non-planted aquarium can significantly alter the water parameters, specifically hardness and pH. However, a regular pwc will, or should, keep the parameters close to the replacement water; and substantial pwc will in themselves maintain more stable water parameters from nitrates and bacteria. And no thinking person can argue that more polluted water is better because it is "stable." A regular weekly pwc of 50% or more, combined with an acceptable fish load, will greatly improve the condition of the water and thus the fish's health. Adding plants makes all this even better.

Byron.


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## 1077 (Apr 16, 2008)

Byron said:


> Before I offer some general advice on partial water changes, I must correct some inaccurate comments in previous posts.
> 
> 
> 
> ...


 
I agree with much of this. Fish adapt to their enviornment as best they can. By providing them with frequent water changes,we are removing or reducing the Total dissolved solids that Byron speaks of. Frequent, in my mind is the key word whether the water changes be large,or 25 percent. As stated,fish will through their osmoregulatory function(Adjusting to salts,minerals ) try and adapt to their enviornment, even poor enviornment. A sudden change in their enviornment,,even for the better,,, can and does sometimes have negative effect. Is why I still believe frequent small changes are better than infrequent large changes and why drip acclimation of fishes to new enviornments is less stressful in my viewthan other methods. 
As I have mentioned in the past, there are no tides,rains,or currents such as in nature to carry pollutants awayin a glass box of water. Water changes done frequently whether large or smaller ,will always keep fish healthier and Total dissolved solids which are comprised of everything added to the tank in addition to waste created by fish,,will remain low. We have all seen what poor water conditions can do with respect to fishes health. 
I believe large infrequent water changes to be more stressful than frequent smaller ones and it is based entirely on my expierience with fishes I keep and have kept.


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