pH meter calibration for the first time.

[manphredd]

Hi, i bought a pH meter about two years ago and i used it for the first year, until it started giving inaccurate readings. I never calibrated it becouse i have a lot of stuff going on and never got to it.

But now i have gotten the pH 7 calibration liquid, and i am going to try it tonight.

Is there even a point in doing it? Is it a gonner?

Have a great day everyone.

 

[HidingInTheHaze]

....until it started giving inaccurate readings.

How do you know it was ever accurate if you never calibrated it. Most of the ones I have had are not accurate right out of the box, also most require a 2 point calibration with both 4.0 and 7.0 so probably no point in doing it now, it's a if it ain't broke dont fix it kinda thing.

 

[Vegan]

I just picked up a blue lab that read 6.6 out of the box in 7.01 cali fluid..
my last blue lab would drift about +.2 about every month or so, I jst calibrate every 3 weeks or so..

now my hanna pens had to be calibrated weekly..if the ever worked at all, got to the point with hanna I had to have them checked before I would leave the shop..

so yea I would say try and calibrate it ,,imo it was toast along time ago

 

[jav2043]

Hi, i bought a pH meter about two years ago and i used it for the first year, until it started giving inaccurate readings. I never calibrated it becouse i have a lot of stuff going on and never got to it.

But now i have gotten the pH 7 calibration liquid, and i am going to try it tonight.

Is there even a point in doing it? Is it a gonner?

Have a great day everyone.

I read that bluelabs ph pen go bad if you don't keep them moist and stored in solution. Not sure if that applies to your hanna one

 

[TheyCallMeJJay]

Hanna makes the best. You have to acheive a good slope. The good ones will give you a slope. The higher the slope the better.

Calibrating solutions such as 1.68, 4,7, and 10 have shelf life. And believe me, they're as accurate as milk in terms of shelf life.

A plating supplier will have very accurate meters such as Hanna industrial. Look to pay at least $300 for a good one. Also, the good ones allow you to change out the solution within the probe. This is something a lot of people don't realize.

 

[TheyCallMeJJay]

Always keep your probe wet. Prefferably in 7 cal solution. Always calibrate before use. People who use them professionally in the field when dealing with chemistry calibrate sometimes after every reading.

 

[Budley Doright]

Hi, i bought a pH meter about two years ago and i used it for the first year, until it started giving inaccurate readings. I never calibrated it becouse i have a lot of stuff going on and never got to it.

But now i have gotten the pH 7 calibration liquid, and i am going to try it tonight.

Is there even a point in doing it? Is it a gonner?

Have a great day everyone.

Pitch the thing.....

instead buy this....

General Hydroponics pH Test Kits make pH testing easy


Ive been using this stuff for years now..... the sort of accuracy that the meters might give are not necessary......

 

[Philosophelon]

Has the pH probe been stored in calibration fluid (or something similar)? If you stored it dry for a year, it's probably done for. They are kinda finicky. Btw, what make and model is the meter?

 

[stickyuser]

Maybe i should have a good at my metering..

 

[TheyCallMeJJay]

Here's some good habits to practice when using PH meters.

1) Always keep the probe wet.

2) Always Calibrate before and after use (its what we pros do in the lab).

3) Get some DI or Distilled Water.

Rinse your probe in the DI Water. Stick it in your Buffer solution and swirl it around a little. Let it sit for 3 seconds AFTER the pen has stabilized, calibrate to your buffer. If you are doing a 2 pt calibration re-rinse the probe and then stick it in the second buffer. Repeat the steps.

The best PH meters utilize a 2 pt calibration. Calibration accuracy is measured in a slope %. And the good ones will give you that number. A good pen will read anywhere between 95% slope to 100%. Anywhere outside those numbers and its time to replace the probe, or change out the cell solution (do this first).

Its important to calibrate within the range of what you are reading. I.E. If you are testing a solution that typically reads 5.5 you will calibrate with a 7 buffer and then to a 4 buffer. If you are reading below a 4 you will cal 4 buffer and then to a 1.68 buffer. If its above an 8 I would do 7 buffer then to a 10 buffer.

 

[growshopfrank]

Always keep your probe wet. Prefferably in 7 cal solution. Always calibrate before use. People who use them professionally in the field when dealing with chemistry calibrate sometimes after every reading.

http://www.hannainst.com/Usa/whitepaper/CareandstorageofpHelectroderev4.pdf

Cliff notes version- use storage solution, buffer 4 or for a SHORT time buffer 7
In a pinch white vinegar will work

NEVER EVER use RO or distilled water for a storage solution as it will ruin your meter

 

[CheeseFiend]

i am a new grower and cant afford a ph meter

so i will be using a gh ph drop kit £5.00

 

[Philosophelon]

Cliff notes version- use storage solution, buffer 4 or for a SHORT time buffer 7
In a pinch white vinegar will work

Why should one only store the probe in 7 for a short time, and rather use 4 (or even vinegar in a pinch!) for longer term storage?

What about using nutrient sol'n (pH ~5.85), or would the salinity mess it up?

 

[Granger2]

When I store in pH 7 standard I get slime. In pH 4 standard I don't.

pH drops are fine unless your nute solutions are colored. I grow with organic nutes so it's typically murky dark gray to murky black. No worky. Good luck. -granger

BTW, some of the meter storage solutions are pfthalates. This shit is toxic. I ordered a bottle and never opened it when I saw the ingredients.

 

[Philosophelon]

Thanks bud!

That's cool to learn, I always just figured a little biofilm was unavoidable, so I never bothered to actually look into it. Also, I didn't know anybody put pfthalates in their storage sol'n. Julian, that is FUCKED!!!

 

[Budley Doright]

i am a new grower and cant afford a ph meter

so i will be using a gh ph drop kit £5.00

I dont know if you will be using the same kit I have...


but 6.0 is green...

and 7.0 is blue



I just make sure the stuff is just a little greenish...but mostly blue....


that should be 6.5 to 6.8


or slightly acidic.....


Many plants like slightly acidic...because the micronutrients are quite available to the plants at that ph....

 

[CheeseFiend]

hi there burnt rope i am using canna terra soil i emailed them they recommend a ph5.8 to ph6.2 i think i will ph6.2ish