PH Meter Problems

[leftright]

Hi, the readings on my digital PH Meter have gone way off. Even now when I try to calibrate it in a PH7 solution it reads it as PH10. I use it carefully and per instructions rinsing with distilled water but this is the second meter this has happened to. Both were decent brands (ie not cheapo crap) Any ideas what could be the cause?
Thanks.

 

[darkhollo]

how are you storing it between readings?
if you are storing in wet.. in what type of solution?

It should be stored in pH probe storage solution and a probe can be revived by storing in pH 4.0 calibration solution. (someone back me up on this one)

--dh

 

[FreezerBoy]

Any ideas what could be the cause?
Thanks.

Yeah, you bought a pH pen rather than a $5 test kit from the aquarium store. All pH pens are crapshoots at best. Anything less than $1000.00 and you're getting a toy. Toys break.

There are scenarios where pens are convenient but, drops are just as accurate and: they never break, their batteries never die, require no calibration, no replacement probes ...

 

[geopolitical]

Have to agree with Freezer. I have an acid dosing system based off an aquarium co2 system and I have to replace the probes about once a year on average. I've never had one last more than 18 months of hard use and that was pretty exceptional. I still use drops to keep an eye on the doser and make sure it's not time to replace the probe.

If the only thing you're doing with your pH tester is testing pH stick with drops or strips.

 

[LlamaSchool]

Buy a $5 liquid test kit. I really don't see the need for electronic pH testing unless my nutrient mix was so thick with organics that I couldn't read the color.

 

[Retardo Motabon]

My guess is you cracked the probe accidentally. every pH probe that goes bad on me has been due to a very small crack in it. maybe from the sink or the counter or slapping against a water bucket.
It doesnt take much to break a pH probe. Ec or tDS probes, they wont break but pH probes are really fragile. My last probe came broken, even packed from the manufacturer. Look into the glass bulb and tilt the probe.
if you see an airbubble in there that seems too big, its probably cracked. A little air bubble is normal, a big one will cause drastic readings low or high. often it gets masked when you store the tip in alot of cal. or storage solution, and will give a reading right at 7 sometimes.
I'd say its cracked.
I would recommend having simple pH drops around in case of such a situation.
Rm

 

[Vegan]

Yeah, you bought a pH pen rather than a $5 test kit from the aquarium store. ...

LOL