pH tester calibration

[Flem]

Can I do a one point calibration on my pH tester using only a 7.01 solution? Will it still yield accurate results?

 

[ibglowin]

Not as good a calibration as using the 4.0 but it will work in a pinch if you don't have one but for sure get one ASAP as the pH of every wine is in the 3-4 range.

 

[Jify]

Buffer solutions are pretty cheap, if you have the ability to do a two-point calibration I'd recommend it.

An extra buck or two will net you better accuracy and solid results.

http://www.monashscientific.com.au/pHCalibration.htm#PointCalibration

 

[Flem]

My problem is that I think I contaminated my "4" solution. Probably dumped my "7" from the last test into the "4" container. Oh well, "when you're dumb, you suffer".

 

[Wade E]

I know its more expnesive to buy this way but I like the pittle packets just for the reason as they are sealed until use. I dont trust the big bottles for longer storage once they hae been opened all too much.

 

[ibglowin]

As long as its sealed up it should last a year at least, more if you keep it in the fridge. If you do keep it in the fridge, remember to let your solution come to room temp before calibrating. Its a buffer, its whole purpose in life is to resist change!

 

[Flem]

If the pH tester compensates for temperature, do you need to have the solution at room temp?

 

[ibglowin]

The problem comes as it warms up to room temp. Even with temp correction I have seem them drift quite a bit. Its always better to have things stable and not changing rapidly. If you want an accurate reading take as many variables out of the equation as you possibly can.

 

[Flem]

Thanks, Mike!

 

[ibglowin]

Wine or grape juice can be especially challenging as the Potassium in grape juice can act as a buffer effectively keeping the pH from changing. If you are trying to adjust the acid on your must you have to go especially slow and add 1/2 what you think it will need. The Potassium will bind with the Tartaric effectively keeping it from changing for quite some time, then it will release it later on and BAM your pH drops like a rock and if you kept adding Tartaric the whole time you are more than likely now way overshot your target acid and pH range.

Always go slow adding acid to must, stir well and let it sit for a few hours, then check it again.