# 90% water change on my 10 gallon community tank?



## IanHulett (Feb 19, 2013)

Hi guys. Yesterday, I bought a fancy yellow guppy who's name is Lemon and I also bought a Dalmatian Molly who's name is Lady. Before I got them, I had about 10 fish fry from mostly guppies. I took a water sample to Upstate Corals on Jay Street and found out that I had an ammonia and nitrite spike. My nitrates are fine though. So, I did a 90% water change. What's the worst thing that can happen? Is 90% a little bit overboard as far as water changes go? Thanks in advance.


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## IanHulett (Feb 19, 2013)

I probably should have named this thread "Dangers of 90% water change in a 10 gallon community tank."


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## lilnaugrim (Mar 27, 2013)

Well it's best to avoid super large changes like that. Instead do a series of small ones like 50% and then wait an hour or two and do another one if the levels are still high. You should get the API Master Testing Kit so you can keep an eye on them yourselves so it will be easier and you'll know when to do a water change  It sounds like your tank is cycling.


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## jaysee (Dec 9, 2009)

I ONLY do massive water changes like that - 80% every 4-6 weeks. There's no danger in doing a huge water change unless you've gone months without changing the water. The only concern is shock from a rapid pH swing, which can happen when you don't change the water for a long time.


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## lilnaugrim (Mar 27, 2013)

+1


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## Hallyx (Jun 11, 2011)

Amazon.com: API Freshwater Master Test Kit: Pet Supplies


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## Kumo (Oct 26, 2013)

Massive water changes (50-60% most) should only be done once a month. Once a week water changes should only be done with 20-25% water changes. I buy prime, quick start, stress zyme and stress coat to help keep my ammonia and nitrite levels at zero, or close to zero.

Massive water changes can possibly send a fish into shock, so that's why "massive" changes should only be 50-60%.


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## jaysee (Dec 9, 2009)

Kumo said:


> Massive water changes (50-60% most) should only be done once a month. Once a week water changes should only be done with 20-25% water changes.
> 
> I buy prime, quick start, stress zyme and stress coat to help keep my ammonia and nitrite levels at zero, or close to zero.
> 
> Massive water changes can possibly send a fish into shock, so that's why "massive" changes should only be 50-60%.


Why should the water changes be as such, as opposed to the countless other ways to do them?

You should not need to add quick start or stress zyme to keep your ammonia and nitrite levels at 0. That's what the bacteria colonies do.

As I said, the only way there would be shock is if the parameters, particularly pH, were very different, which can happen if water changes are never done. Assuming a regular water change schedule, massive water changes are absolutely harmless. In my experience "regular" is at least once every 4-6 weeks.


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## rickey (Jul 7, 2013)

I don't go along with any of this.
There is nothing wrong with 80 to 90% changes as long as the pH is stable 
Like wise I don't go along with a 6 week time frame either 
But big water changes do mean a more stable water over the long run.
I do a daily small (20%) water changes because my stocking levels are high and they're automated but this allows me to hold the tanks at 20 ppm nitrate.

R


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## Tolak (Nov 13, 2012)

Kumo said:


> Massive water changes (50-60% most) should only be done once a month. Once a week water changes should only be done with 20-25% water changes. I buy prime, quick start, stress zyme and stress coat to help keep my ammonia and nitrite levels at zero, or close to zero.
> 
> Massive water changes can possibly send a fish into shock, so that's why "massive" changes should only be 50-60%.


Look into keeping & breeding discus, many breeders do large water changes daily. Something is wrong if you need to turn a water change into chemical soup, a good water conditioner such as Prime should be all you need in a cycled tank.


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## rsskylight04 (Nov 9, 2013)

Just my opinion: water changes won't hurt fish unless there is somthing wrong with the water your adding, or if ph is off from going too long without changing. If ammonia and nitrites are high, large frequent waterchanges might be the best way to save the fish. When fish are added before the tank is cycled, I think daily water changes are good practice. 90% seems excessive to me, but if it is dechlorinated and up to temp
, it won't hurt the fish.


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## rickey (Jul 7, 2013)

Keep in mind there is a direct correlation between stock level and water change frequency and size, I have a much larger bio-load than I would ever recommend to average home hobbyist 

Rick


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## rsskylight04 (Nov 9, 2013)

Thanks for your input rickey. What would you reccommend for hobbyist with established tanks and typical bio load? I have 75 gal, 40 gal, 29 gal, and two smaller tanks. Your thoughts about % change and frequency would be much appreciated.


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