# How-To: Make A Calibration Solution For Your pH Meter



## banderbe (Oct 10, 2005)

I found this article on how to use Borax to make a home-made pH calibration solution.. I'm going to give it a try..

http://web.archive.org/web/20021015005420/www.animalnetwork.com/fish2/aqfm/2000/feb/bio/default.asp


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## cbennett (Oct 20, 2005)

I dunno, doesn't seem like it would be worth it to me - altho the DIY mad-scientist bit appeals to me. I would NEVER use the pH 10 calibration solution, it has a very very short shelf life so it quickly becomes unstable. Even if your tank's pH is on the high end, use the 4.0 and the 7.0 solutions. The key is to have two points to calibrate the probe to, it doesn't matter what the two points are. The 4.0 and 7.0 are very stable and little disposible packets are less than a dollar. You can buy them individually or in packs of 10 or 12 at places like www.drsfostersmith.com. It seems a lot simpler to put the probe in a freshly-opened packet and calibrate rather than try to mix the borax, determine (and maintain) the temperature the temperature of the solution and hope that the calculations and the measuring devices are correct.


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## banderbe (Oct 10, 2005)

cbennett said:


> I dunno, doesn't seem like it would be worth it to me - altho the DIY mad-scientist bit appeals to me. I would NEVER use the pH 10 calibration solution, it has a very very short shelf life so it quickly becomes unstable. Even if your tank's pH is on the high end, use the 4.0 and the 7.0 solutions. The key is to have two points to calibrate the probe to, it doesn't matter what the two points are. The 4.0 and 7.0 are very stable and little disposible packets are less than a dollar. You can buy them individually or in packs of 10 or 12 at places like www.drsfostersmith.com. It seems a lot simpler to put the probe in a freshly-opened packet and calibrate rather than try to mix the borax, determine (and maintain) the temperature the temperature of the solution and hope that the calculations and the measuring devices are correct.


Did you actually read the article? The whole point is because those buffer solutions you mention have been known to have pH values other than what they claim to.


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## cbennett (Oct 20, 2005)

Yes I actually read the article. The article seemed to be mainly talking about people using the pH 10 calibration fluid and getting wonky results. My point is that the pH 10 solution is known to be unstable and that one should be able to avoid having any problems by simply switching to the 4 and 7 solutions.


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