# Can you make your own 7.0pH Neutral Buffer? More powerful than brand names?



## KevinC (May 24, 2004)

For a carbonate-based buffer:

Place a large amount of solid baking soda in a container. Add water to dissolve. The pH will be about 8.3. Adjust pH using dilute HCl (muriatic acid) to pH=7.00 (or other desired pH).

For a phosphate-based buffer (algae grower!):

Place a large amount of KH2PO4 in a container. Add water to dissolve. Adjust the pH using dilute NaOH to pH=7.00 (or other desired pH).

Why not just add baking soda directly to your tank?? Why do you "need the pH to be neutral or acidic"? You are aware that changing the pH does NOT change your CO2 concentration?

Kevin


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## Spar (Aug 7, 2003)

this is not for a planted tank. it is for my string rays and arowana. due to my low KH and large waste production from these fish the pH crashes within days of not using a buffer.

raising KH to 4.0 dH makes the water too alkaline for their liking. They could handle it, but still a preference of mine to be more like the books.

Is it possible to make the powder form of neutralizer though? I could use the above way to get my water change water to 7.0, but what about to re-adjust the water already in the tank?


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## KevinC (May 24, 2004)

Spar said:


> Is it possible to make the powder form of neutralizer though?


Yes. Try looking at www.fishersci.com under "buffers". They might have one in bulk powder form. I know they sell individual "pills" to make 100ml of a fairly concentrated pH-meter calibration solution (pH=7.00). It is phosphate based IIRC.

Otherwise you need both the acid and base form of your buffer (in the phosphate case that means KH2PO4 and K2HPO4) and to calculate the ratio of the two using the Henderson-Hasselbach equation:

pH(desired) = pKa + log([base form]/[acid form]) 

where [x] = moles (use molar mass to convert to grams). The H-H equation is not perfect, but will get you close enough that your fish won't care. 

The above won't work for the carbonate-based buffer since the acid form is H2CO3 (not a salt - just CO2 and water).



Spar said:


> I could use the above way to get my water change water to 7.0, but what about to re-adjust the water already in the tank?


The nice thing about buffers is that within certain limits, they don't change pH when you dilute them. You could add the concentrated solution to the tank and get the same effect.

Kevin


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## compulsion (Mar 2, 2004)

if your a by the book man then how comes you want to regulate your PH with additives?

Its never good man, if your keeping aro then why not invest in a RO unit? ide say that was by the book more than useing buffers to change the PH.


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## Rex Grigg (Dec 10, 2002)

I'm wondering why not just do large daily water changes? Chances are these fish are also sensitive to high TDS and high TDS is what these buffers are going to give you.


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## Spar (Aug 7, 2003)

I do have an RO unit. I do 50/50 tap/RO water changes at 40% 2x per week.

However, I have been working on finding a way to not use additives for years. Unfortunantly, raising the KH to 4.0 gives a pH of 7.4 or so. If I leave the KH at 1.0, the pH crashes to 4.0.

The best alternative is do as Rex says with daily water changes. My work-load keeps me from that, and my wife would laugh at me if I asked her to 

I am pretty sure I am just going to begin increasing my pH to 7.4 and just live with it though.


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## Laith (Jul 7, 2004)

Why not add CO2 even if it's non-planted? Get your Kh up to 4 with baking soda and then add enough CO2 to get your pH down to 7. That gives you a CO2 mg/l of 12 which I can't see as being harmful to the fish...


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## Spar (Aug 7, 2003)

that is my long-term plan. just need to get on the ball and order the parts 

I use a sump though, so with the air exposure it will take quite a bit of co2 injection to even raise it to 12ppm.


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## Laith (Jul 7, 2004)

Laith, read the d**n posts before replying!

Sorry, missed the part that you're planning to get CO2 in the future! :icon_roll

I know absolutely nothing about rays or arowanas. But most, if not all, other fish can pretty easily adapt to different pHs (within reason). So I think your own suggestion of letting it go up to a pH of 7.4 is the best solution. Once that works, you don't even need to add CO2!


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## Spar (Aug 7, 2003)

yep, they can adjust. I have heard of people keeping Arowanas in 8.0 water before. In the long-run they would much rather be in stable alkaline water than unstable acidic water anyway.

What is a good estimate of how much ppm of co2 large fish produce anyway? Would it be probable to assume there is ~5 ppm or so co2? I am trying to utilize the co2 chart as much as possible in determining what KH to aim at.


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## bharada (Mar 5, 2004)

Atmospheric concentration of CO2 is around 3ppm, so if you added some surface agitation or aeration to your tank it should stay pretty close to that.


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## Spar (Aug 7, 2003)

hmm. that makes 4KH @ 7.6 pH.

think it is even possible with a Sump to inject co2 efficiently? cant imagine it would be.


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## shalu (Jan 16, 2003)

Spar said:


> think it is even possible with a Sump to inject co2 efficiently? cant imagine it would be.


why not, I used wet/dry with sump on my 100gallon for nearly 3 years now.


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## Spar (Aug 7, 2003)

good to know. did you just have to pump an insane amount of co2 into it?


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## shalu (Jan 16, 2003)

Not really, here is a controlled study:
http://www.hallman.org/plant/booth2.html


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