PH Meter reminder !

Niblixdark

Well-Known Member
Just a friendly reminder for us hydroponic guys especially, remember to recalibrate your PH meter. Preferably every couple weeks.

Especially when going into mid flowering!

:wall:
 

Organic Miner

Well-Known Member
You know I started recalibrating every 2 weeks in the beginning, but found it wasn’t necessary because it was spot on. Maybe it was my environment. Definitely checked it at the beginning of each run, both veg and flower. Doesn’t hurt to check more often than less.
 

Niblixdark

Well-Known Member
Are you talking about checking PH or calibrating the PH metering device?
meter me thinks.. Lol

I leave the ph probe in the res and it drifts off a little bitty bit every month, maybe from air stones or 9v battery vs power plug. No idea but they do drift off eventually !
 
Last edited:

gribniff

Member
Ok, guess I'm the anal one.

I calibrate EVERY SINGLE TIME something goes into the pots.
Used to do it bout once a week.

Hate being taught a lesson!
Pen decided, overnight, that 7.0 is 6.1

No, did not keep the pieces.
 

coreywebster

Well-Known Member
Think I have been lucky with mine, its gone a year at times and every time I do calibrate it its bang on where it should be.
Its only an essentials pen too, which are mid range.
 

dbkick

Well-Known Member
Unless the meter/probe is cheap af it isn't that critical. A bluelab guardian flashes a light every 30 days to remind you to calibrate. I've gone months and the meter ends up off by only .1 or .2 .
 

Tranesong

New Member
After two cheap PH meters I HAD to break down a by a $100 HM lab model. That said, I didn't know previously how to care for the electrodes when in storage, cleaning etc. My nute formula relies on perfect PH. Now my reading are finally correct after 6 weeks. My plants are growing but showing sign of nutrient dif. Three meters inn six weeks. Damn.
 

Niblixdark

Well-Known Member
Nutradip probes work great for me I've had mine for years now. You can plug it in or use a 9v for mobility.
 

FennarioMike

Well-Known Member
meter me thinks.. Lol

I leave the ph probe in the res and it drifts off a little bitty bit every month, maybe from air stones or 9v battery vs power plug. No idea but they do drift off eventually !
I went to school for water treatment engineering and pH probe calibration and maintenance was drilled into us.

The meter works by an ion exchange through the glass tip. There's a tiny ceramic embedded in the glass that allows ions to flow in and out of the probe. The glass is full of KCl solution and each time that it's immersed in solution, some of that KCL is lost through diffusion - at the same time osmosis pulls water into the probe. This change in KCl since the last calibration is what causes drift. Using the KCl storage solution will recondition the probe by "recharging" the inside of the glass.

Never leave a probe in RO or DI water for a long period of time - it will strip out the KCl completely, probably rendering the meter useless. There are a handful of practices that will keep your probe lasting a very long time.

There's also good technique to getting a consistently accurate calibration. Your meter will only be as accurate as your technique. If you contaminate your standard solutions, then your calibration will be off - even though it completes the calibration. You're telling it what 4 and 7 pH look like - if your 4 and 7 solutions are no longer 4.0 and 7.0 - then you're mis-calibrating the meter.

Always rinse your probe and sample container with the solution to be tested, discard - then fill the sample container and take a reading. You're rinsing off things that might skew your pH. Like - if you take your probe out of 7.0 solution and dip it into the 4 - well, now the 4 is no longer really 4... Also, never pour solution back into the bottle. Once it has left the container, consider it contaminated.

Always do a 2 point calibration with both 4 and 7 - then it will be accurate between those points. The further away from 4 or 7 that your reading is, the less and less accurate it becomes. If you only calibrated with 1 solution then it would literally only be accurate at that single point.

It's a good idea to do all of these things - AND recalibrate at least monthly. New bottles of standard solutions are a whole lot cheaper than sick plants.
 

FennarioMike

Well-Known Member
It stays in KCl all the time when its not in use.
That's weird that it drifts like that. I have the blue labs guardian - I think that's the model... It stays in the rez 24/7 and monthly I do a 24 hr recharge with KCl, recalibrate - and back in the rez. I've been using this one for about a year and so far so good. It reminds me monthly to recalibrate. Since I use it 24/7 it will probably shorten it's life - but I can just replace the probe itself.
 

firsttimeARE

Well-Known Member
That's weird that it drifts like that. I have the blue labs guardian - I think that's the model... It stays in the rez 24/7 and monthly I do a 24 hr recharge with KCl, recalibrate - and back in the rez. I've been using this one for about a year and so far so good. It reminds me monthly to recalibrate. Since I use it 24/7 it will probably shorten it's life - but I can just replace the probe itself.
Think you misred that. The meter itself goes off after 2 weeks (when you calibrate it you get an icon that reminds you that its calibrated or needs calibration) that icon goes awya after 2 weeks.

Meter is calibrated still tho, but I do it once a month to be sure and its usually 0.1 at most off after that point
 

Jestone

Member
I went to school for water treatment engineering and pH probe calibration and maintenance was drilled into us.

The meter works by an ion exchange through the glass tip. There's a tiny ceramic embedded in the glass that allows ions to flow in and out of the probe. The glass is full of KCl solution and each time that it's immersed in solution, some of that KCL is lost through diffusion - at the same time osmosis pulls water into the probe. This change in KCl since the last calibration is what causes drift. Using the KCl storage solution will recondition the probe by "recharging" the inside of the glass.

Never leave a probe in RO or DI water for a long period of time - it will strip out the KCl completely, probably rendering the meter useless. There are a handful of practices that will keep your probe lasting a very long time.

There's also good technique to getting a consistently accurate calibration. Your meter will only be as accurate as your technique. If you contaminate your standard solutions, then your calibration will be off - even though it completes the calibration. You're telling it what 4 and 7 pH look like - if your 4 and 7 solutions are no longer 4.0 and 7.0 - then you're mis-calibrating the meter.

Always rinse your probe and sample container with the solution to be tested, discard - then fill the sample container and take a reading. You're rinsing off things that might skew your pH. Like - if you take your probe out of 7.0 solution and dip it into the 4 - well, now the 4 is no longer really 4... Also, never pour solution back into the bottle. Once it has left the container, consider it contaminated.

Always do a 2 point calibration with both 4 and 7 - then it will be accurate between those points. The further away from 4 or 7 that your reading is, the less and less accurate it becomes. If you only calibrated with 1 solution then it would literally only be accurate at that single point.

It's a good idea to do all of these things - AND recalibrate at least monthly. New bottles of standard solutions are a whole lot cheaper than sick plants.
What is a long period of time in your opinion? A couple hours? Even less? Would I be pushing it if it's immersed just long enough to determine and adjust the pH of my RO water, approximately 20 minutes? Normally I wouldn't even suspect this being a problem but as of recently I'm having a lot of probe reading issues and can't figure out what I'm doing wrong.

FYI I'm using the Blue Lab Guardian System. This is where the manual mentions not storing the probe in RO water.IMG_3466.PNG mentions RO water
 
Top