# PH is at 7.4



## Jason hilts (Feb 15, 2008)

My PH is at 7.4.I tested the water with the red sea ph test.Iam running a co2 system on my tank and it is set at 1 bubble per secound.The general hardness is 9,and the KH is 5.What can i do to get my ph down should i increase the co2 bubbles or should i use acid buffer from seachem or use peat filtration.


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## cfreeman (Mar 19, 2008)

You might want to check the diffuser location. If you have an outflow stream from a filter pump, placing the bubbles from your diffuser into the path of this stream will help to get more CO2 into solution. I have found that this makes a big difference in the CO2 content, and pH as a result.

The bubble count needed depends on the size of your aquarium, among other factors. If the above adjustment is insufficient in decreasing your pH, the next step seems to be increasing the bubble rate.

I would definitely focus on your CO2 distribution before even thinking of monkeying with pH adjustment chemicals.

I hope this helps.


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## hoppycalif (Apr 7, 2005)

A 7.4 pH is fine for fish, so you don't need to adjust it at all. Adding CO2 is for the plants, and it is a "by product" of dosing the CO2 that lowers the pH.


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## cfreeman (Mar 19, 2008)

Hoppy, I fully agree with you that a pH of 7.4 is fine for fish. If Jason is using CO2, I am guessing he has plants too. With a pH of 7.4 and a KH of 5, by my calculation the CO2 is 6 ppm. Is that enough to support good plant growth? I thought it was sub-optimal. It does make sense to verify the CO2 levels with a drop checker, but the pH value in itself suggests to me that he is having a challenge getting the CO2 into the water. Do you agree? Thanks, I have learned a lot from reading your posts!


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## hoppycalif (Apr 7, 2005)

cfreeman said:


> Hoppy, I fully agree with you that a pH of 7.4 is fine for fish. If Jason is using CO2, I am guessing he has plants too. With a pH of 7.4 and a KH of 5, by my calculation the CO2 is 6 ppm. Is that enough to support good plant growth? I thought it was sub-optimal. It does make sense to verify the CO2 levels with a drop checker, but the pH value in itself suggests to me that he is having a challenge getting the CO2 into the water. Do you agree? Thanks, I have learned a lot from reading your posts!


Yes, I agree. I'm currently on a "crusade" to discourage people from obsessing about pH, just for the sake of hitting the ideal pH. That leads me to jump in a bit off subject at times

Thank you for the compliment! As I have noted before, I still learn far more from reading here than I suspect anyone ever learns from what I post. And, being wrong as often as I have been has dampened any tendency I might have had about being the final word on anything.


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## fish_4_all (Jun 3, 2006)

Do you know what you KH was before you started adding CO2?


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## hoppycalif (Apr 7, 2005)

fish_4_all said:


> Do you know what you KH was before you started adding CO2?


I don't think CO2 will change the KH. The only thing that I know of that changes the KH is plants like vals that use carbonates as a source of carbon - they can reduce the KH.


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## fish_4_all (Jun 3, 2006)

Hmm, it thought it raised your KH? I would assume by the charts I have seen that it would have to to get the numbers you can see from injecting CO2? 

I could be wrong but I would hate to try and get 30ppm CO2 with a KH of 1 when I would need a pH below 6 if the KH didn't go up when injecting CO2.


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## hoppycalif (Apr 7, 2005)

The pH drop that injecting CO2 causes is not harmful to fish or plants, as far as anyone has been able to determine. (I'm almost sure of this.) In fact pH is a consequence of other things, such as various dissolved substances. And, those dissolved substances, in excess can be harmful. So, much more than 30 ppm of dissolved CO2 can harm the fish, but not because it drops the pH too far. It harms the fish even at higher pH's.

As I understand it, when you dissolve CO2 in water containing carbonate ions, a mix of carbonate ions, carbonic acid and CO2 as CO2 results in the water. The mix depends on how much carbonate was in the water to begin with - the KH. But, that amount doesn't change as you add CO2, only the amount of carbonic acid and CO2 as CO2 changes.

I'm not a chemist, so I hope someone who knows more about this will offer a better explanation.


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