how do i test a digital ph meter

i think my ph meter may be broken and giving me wrong readings. how can i test its really working?

I would dip it in a 7.0 buffer solution or some solution that you know will have the right PH level right out the bottle.

some ph buffer, grow shop or online

i'm probably just going to buy a second one tomorrow, only have PH+ and minus kicking around. anything around the house that u may know the exact ph of?

I know lemon juice has a really low PH you could try making a solution of that and seeing if its calibrated right

Dip in Windex and see if it shoots up pH reading really fast. It should

Its like 7 bucks for buffer solution. Use that. You're going to need it anyways if you want to do monthly tests on your meter like you should.

Its very IMPORTANT when testing for a bad ph meter to test both ph buffer 7 AND ph buffer 4.01 or ph buffer 10. Reason for not using only the ph buffer 7 is that a ph probe that is out of solution "cant remember at the monent what the fluid in the probe is" but if it is out or low it will still read a ph 7 correctly or close to it. A ph of 7 is 0mv output to the ph meter. So nothing..... So always use a 4.01 or 10 when testing for a bad probe!

Like others have said. You can use lemon juice or windex to see if the probe is "functioning"

Vanishing Toaster: they're all giving you good advice but you might want to consider one other idea. General Hydroponics makes a little test kit with a bottle of pH up, a bottle of pH down, a test flask, a bottle of test solution and a color chart to compare the color of the sample you take to. If I start to doubt the results of my test meter the first thing I do is I take a sample and compare the two readings.

I always trust the test kit because it may be slower than the meter but the accuracy doesn't vary beyond my eye sight. If you;'re not color blind, it's an accurate test, but the real advantage of the meter is speed compared to the slower manual test kit. Also, if its been a couple of months then it's usually time to re-calibrate your instrument. I hope that helps. HSA

went to the hydro shop to see about a new meter and he didn't have any till the next day so i bought a soil ph testing kit and got a peachy colour with the slightest green tinge, broken probe did lead to me giving them water without enough ph+ wanted to try and bring the soil back up.
went bk in the next day and they hadn't arrived and wouldn't for a month, he did have a bluelab ph pen he did me a deal on tho. my original meter was a cheap 20 quid job. hopefully this one was worth the extra buck. got some ph7 to calibrate it, he didn't have any 4......organised as any typical stoner would be lol