# CO2 fluctuations with water changes?



## FatherLandDescendant (Jul 24, 2014)

Otoscapes said:


> If I am making a non-co2 low tech tank, would the added co2 from water changes cause any harm to the tank's balance (which would lead to algae)?
> 
> Some people say that topping off the tank with RO/DI water is fine while other people say that weekly/biweeklywater changes are always necessary.
> 
> ...


CO2 shouldn't hurt anything. The fish expell CO2 through respiration and the plants expell CO2 when the lights are off, so you have CO2 in the tank reguardless. Excel is a liquid carbon source that in low tech setups is used in place of gassed CO2.


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## Hoppy (Dec 24, 2005)

Doing 50% water changes, with tap water straight from the faucet, introduces enough CO2 that it can and does trigger BBA attacks. I tried it for some time, and, even though I had very low light, I did get BBA. I switched to using Excel, at twice the Seachem recommended daily dosage, and fewer large water changes, and was able to largely avoid BBA, even though I also increased my light intensity, so it was near the maximum for non-CO2 tanks. I'm pretty sure that others have had similar experiences.


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## plantbrain (Dec 15, 2003)

One of the tenets of a non CO2, no Excel planted tank is low maintenance. 

So doing lots of water changes is certainly NOT part of the goal there.
Nor is overstocking with lots of fish etc.
Nor is having just a couple of plants and that's it. 
Read the advice for the entire method, not just some of it.

I top off with tap water, not much else. Tanks do not have any BBA, in fact, I've added BBA infested Anubias plants...only to watch the BBA die off and have healthy perfectly clean plants a week or two later. 

Fancy that.

No excel, no water changes, nothing.

You will have higher rates of growth, less CO2 competition if you use Excel or CO2 gas enrichment. So you can keep more species and garden more.

But that means more labor, and water changes(more to clean up after the gardening mess you make).

Plant species in terms of labor make massive differences, Ludwigia Red pantanal vs say a tank full of Anubias? HUGE difference and management will be very very different also in CO2, Excel and non CO2/Carbon enriched tanks. 

Density of the plants also, generally, always add as many plants will fit.


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## Hoppy (Dec 24, 2005)

plantbrain said:


> One of the tenets of a non CO2, no Excel planted tank is low maintenance.
> 
> So doing lots of water changes is certainly NOT part of the goal there.
> Nor is overstocking with lots of fish etc.
> ...


This suggests that a tank with a glass top instead of open topped might do even better as a non CO2 tank. Open topped tanks, as mine is, evaporate a lot more water and need bigger amounts of top-off water weekly or more often. Closed top tanks would get less top-off water, with even lower fluctuations in CO2 content.


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## Django (Jun 13, 2012)

CO2 from a water change will lower the pH by some amount, I don't know how much. But, yes, the problem I've heard of is fluctuations in CO2 content in the aquarium causing algae problems. I've had my share of algae problems, but personally, IMO, they were from imbalances in my system. I don't have any data to suppport either way.

You didn't say what size tank you are going to run, but some people de-gas incoming water, lettiing it sit overnight, preferably with aeration. This hopefully reduces the level of CO2 in the water to the equilibrium level of dissolved CO2.

Steven


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## mistergreen (Dec 9, 2006)

Do your water changes at night. No light, no chance to trigger algae. Parameters should stabilize the next morning.


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## Hoppy (Dec 24, 2005)

mistergreen said:


> Do your water changes at night. No light, no chance to trigger algae. Parameters should stabilize the next morning.
> 
> 
> Sent from my iPad using Tapatalk HD


An absurdly simple solution, which should work!!roud:


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## mistergreen (Dec 9, 2006)

I have 2 beautiful dirt tanks for about a decade with no algae. The only tank with BBA is the tank with co2. Imagine that.


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## Zorfox (Jun 24, 2012)

mistergreen said:


> Do your water changes at night. No light, no chance to trigger algae. Parameters should stabilize the next morning.


Brilliant! That thought has never occurred to me. Thanks


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## goodbytes (Aug 18, 2014)

mistergreen said:


> Do your water changes at night. No light, no chance to trigger algae. Parameters should stabilize the next morning.
> 
> 
> Awesome tip! Thanks


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## Diana (Jan 14, 2010)

> Do your water changes at night.


When do I get to sleep?


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## mistergreen (Dec 9, 2006)

Diana said:


> When do I get to sleep?


You don't. You're not going on vacations either.

Kidding.
You can do your water change anytime. Just leave light out of the equation. Your plants aren't going to die if there's no light for the day.


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