# High CO2 question



## MrBones (Feb 23, 2013)

Ok folks, I've constantly been bubbling CO2 into my newly set up planted tank, btw I haven't any fish yet still cycling. My CO2 content is up to 96 and my PH is down to 6.4.

6.4 is a little lower than I want, my question is will that rise as the plants consume the CO2 and with that said should I lower my CO2 induction until it levels off? Or should I artificially raise my PH?

Thx


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## Zapins (Jul 28, 2004)

The pH will fluctuate as plants consume CO2 out of the water. Generally you will see pH fluctuate within about 1 degree per day from sun up to sun down. So you'll probably see it go to 7.4ish during the day and then back down again at night.

These fluctuations are not harmful and you should not try to control them. The lowest your pH can get with CO2 addition is 5.5 if you have pure distilled water with no buffering capacity. 

A lower pH is usually preferred by aquatic plants and most aquatic freshwater fish.

Also, welcome to the forum


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## MrBones (Feb 23, 2013)

Zapins said:


> The pH will fluctuate as plants consume CO2 out of the water. Generally you will see pH fluctuate within about 1 degree per day from sun up to sun down. So you'll probably see it go to 7.4ish during the day and then back down again at night.
> 
> These fluctuations are not harmful and you should not try to control them. The lowest your pH can get with CO2 addition is 5.5 if you have pure distilled water with no buffering capacity.
> 
> ...


Thank you for the welcome!

I'm switching sides now...  I've stopped bubbling CO2 into the water and started dosing with Excel, however, my PH has climbed to 7.6. My dKH is around 7 which is ok IMO but I'd like my PH to be lower. Is water changes with distilled water the only natural way the PH will lower itself?


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## Zapins (Jul 28, 2004)

To reduce the pH you need to add an acid of some kind. The higher the KH the more the water will resist a pH change. So you either need to add more acid (CO2 or another type of acid) or you need to reduce the kH so the existing acid in the water is able to reduce the pH.

Again 7.6 isn't that bad so I wouldn't worry about it too much. But if you really want to lower it why not use the CO2? You can buy a pH controller for your CO2 tank to maintain the pH precisely. They aren't too expensive.


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## tipsy mcstager (Apr 6, 2013)

Zapins said:


> The pH will fluctuate as plants consume CO2 out of the water. Generally you will see pH fluctuate within about 1 degree per day from sun up to sun down. So you'll probably see it go to 7.4ish during the day and then back down again at night.
> 
> *These fluctuations are not harmful and you should not try to control them*. The lowest your pH can get with CO2 addition is 5.5 if you have pure distilled water with no buffering capacity.
> 
> ...


new guy here!
after being on some other "planted forums" it's nice to see people that don't think (like my self) that nothing more then a .5 swing in PH from CO2, will gas your fish, and your tank will explode...............lol

the common sense is refreshing


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## Zapins (Jul 28, 2004)

welcome to the forum tipsy.

I know the feeling but there is no evidence why fish and plants cannot handle gradual pH shifts during the course of the day.


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## tipsy mcstager (Apr 6, 2013)

i try not to forget, that increased agitation on the water surface will make for better gas exchange of O2 and C02.
by breaking the surface tension with a a power head, and keeping the water free of floating oils and proteins.
i can really "fine tune" my PH.


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## Allthegoodnamesaregone (Apr 17, 2013)

MrBones said:


> Thank you for the welcome!
> 
> Is water changes with distilled water the only natural way the PH will lower itself?


Hello, 
distilled / RO water (Reverse Osmosis) have no mineral dissolved, hence no buffer capability. It means that too much of it *could* reduce your KH and promote swings in PH. 
You can add RO water to your tap water and reach the KH wanted, but always go slowly. 
There is also a natural swing in PH between day and night, so always measure your PH at the same time.
Also, when I started, I was always freaking out and trying to correct the PH/KH/Co2/O2 all the time...
It took me some time to understand that you do not work _against_ nature, you work _with_ it. 
Now I am much more relax ...  
Take your time, don't stress the fish.


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