Digital ph meter Calibration

Trying to calibrate this meter. Is there a liquid with a known ph level to do so? Directions say get a 6.8 buffer solution and calibrate to 6.9. But how am I to know the level in the solution?


They do sell things that have a set value for calibrating

I have never used them, but do have them on my “need to get” list…


@bruinsfan33 i usually just get the kit with the 4.0 and 7.0

sometimes they usually give you those in the kit with your meter in a small pouch and you add it to water I think?


OK cool. Says use a solution lol I found something that said milk is between 6.5 - 6.7 . Tried that and getting 6.7. Feel pretty comfortable.
Thank you


Nothing came with it but a booklet and calibration tool. Came from Canada for a few bucks lol no complaints

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You’re going to feel silly but distilled water is 7.0. 6.5 being close to that value and one that we soil growers use, that is probably good enough.

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Thanks. Learn something new every day.

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@bruinsfan33, join the club! That’s why I’m here. Learned a tremendous amount here and for the most part a great group of people.

Yes mine came with buffer powders to add to Distilled water.

@bruinsfan33 …I’m going to add that the probe shouldn’t dry out, keep that tip moist…get the liquids @Ron330 recommended, but the set @bob31 said, (pH 4 & 7 is enough)…most times you can store the pH meter in some of the test liquid, I used the pH 7 allowing me a test of the meter accuracy before use.


thanks @kabongster, adding that one to my list…

Yeah I didn’t know that part. I was wondering why seemed like there was moisture in the cap when it arrived.

Typical scientific instruments have at least 2 points of calibration which allows you to extrapolate rather than interpolate: much more reliable usually. In our case we aren’t flying to Mars so my $7 meter should work with one calibration point.

I didn’t know about keeping the electrode damp. I’ve been rinsing and drying per the instructions.

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I think some are different mine said the same thing. @Myfriendis410

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follow your written instructions…my experience is with my meters, one of them says to dry the outside housing and shake out whatever water is inside (I have distilled water to rinse with after using) but the cap has a pad in the end that is kept moist with a special fluid.

My instructions with storage fluid
“Always make sure your sensor is kept in an electrode storage solution. If dry, refill the pH meter cap with the PH-STOR storage solution. The sponge should be moist (not soaking wet).
High concentration
Extends probe life
Has fungicide to keep probe clean”

I must have the super cheapie model then. nothing in the cap and the directions mention nothing except clean and dry!

I have Bluelab meters and you see a little check mark when they are new or just cleaned and calibrated. The PH meter needs to be rinsed clean then stored in the storing solution inside the cap which has a sponge. The PPM meter only needs to be rinsed and hung up after. After 30 days the check mark will disappear telling you it’s time to clean and calibrate. I guess you would need to have both a cheap and a more expensive side by side to tell if the cheaper one reads correct. Here’s a picture of the cleaning a calibration kit.

PH meter you can see the check mark is missing. Time to clean and cal.


This is all I’ve been using. Came with nothing but a calibrate tool and directions