DIY PH Calibration Solution

hawkinsrgk · Jul 15, 2016

I am trying to make some PH Calibration Solution with Borax and have a question.

I am using the information from this website. http://web.archive.org/web/20021015005420/www.animalnetwork.com/fish2/aqfm/2000/feb/bio/default.asp

It says to use 3.8 grams of borax per liter of water and then look at the referenced table to calibrate the probe according to temperature.

Since I really don't have a good way to measure 1 liter of water, but I have a 250ml beaker was going to try that. So I add 200ml of RO water and use 3.8/5 = .76 g of borax. The issue is that my scale will only do to a tenth of a gram so I added .8 grams of borax and took some grains out before it reached .7.

Then I mix the borax and the paper says that at 71.6 degrees the PH should be 9.207. Here my PH probe is not that accurate and I calibrate to 9.21. I was however able to get the water to that temperature.

The real question is that good enough of a calibration to do the DIY Alk test.

Thanks
Randy

JimWelsh · Jul 15, 2016

A beaker's markings are not accurate enough for what you are trying to do. However, if you can measure a half a teaspoon of borax and one pint of water, then you are golden, according to the article you linked. Why are you not just doing that?

You might also find this link interesting: https://www.reef2reef.com/threads/diy-alk-test-discussion-thread.186606/page-5#post-2490342

And, yes the combination of the two calibration fluids (borax and cream of tartar) is good enough for a DIY Alk test.

hawkinsrgk · Jul 15, 2016

JimWelsh said:
A beaker's markings are not accurate enough for what you are trying to do. However, if you can measure a half a teaspoon of borax and one pint of water, then you are golden, according to the article you linked. Why are you not just doing that?

You might also find this link interesting: https://www.reef2reef.com/threads/diy-alk-test-discussion-thread.186606/page-5#post-2490342

And, yes the combination of the two calibration fluids (borax and cream of tartar) is good enough for a DIY Alk test.

To me it didn't seem it would be accurate enough.