Bought a digital pH meter to get a more precise reading, but the directions on calibration are a little confusing. It came with packages of powder and you’re only supposed to use two based on the pH of the testing liquid is above or below 7.0. Thing is the directions say use distilled water, and I thought distilled water is exactly 7.0, so I’m not sure which packets to use.
Are you supposed to use distilled for just the pH buffer and a second type (alkaline water with a pH of 8.0 for instance) as the testing liquid? Or just use distilled water for all three? Just want to make sure I get this thing calibrated correctly. Thanks
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@TripleB. Should use distilled water as per the directions for all 3 mixes.
Usually ph 7 and ph 4 solutions are what’s required for most accurate readings. 
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You need a standard 7 pH solution and a standard 4 pH solution for calibration I clean my Probe between dipping in 4 and 7 so I do not contaminate the two different solutions. Anytime you do a 2-point Cal compared to a one-point Cal you are going to be more accurate.
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Distilled water FYI isn’t 7.0: it’s nothing. You cannot read distilled water with a PH meter. Whatever reading you get will be wrong.
Distilled water is required, along with very careful mixing amounts to produce the calibration solution.
You can just buy them in solution already. I keep a bottle of 7.0 Standard Reference Solution handy and use it as a cross-check on my meters.
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Thanks, but wouldn’t you need to buy the 7.0 and a 4.0 solution though?
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You already have calibration solution. This is so you can cross-check your meter; just dip it in and if it reads 7.0 you’re good. If it doesn’t you can perform a calibration. You certainly can buy 4.0 as well and use them as your cal standard.
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Oh I was thinking you use that as a substitute for the powder. Having it premixed and ready to go seemed easier and less opportunity for error. Just to clarify, your last sentence means you can use them to calibrate the meter?
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Yes; that’s what they are for.
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