Essentials pH pen not calibrating

shiva71

shiva71

Well-Known Member
Hiya
Bought this to replace my bluelab one which is painfully slow. I calibrate it to 7, it reads my 4 buffer solution as 4.6. calibrate to 4, reads 7 buffer as 6.7 - so it's not calibrating to both.
Any ideas?
cheers!
 
Dr. Who

Dr. Who

Well-Known Member
Use the 7 to start.

Next is a question. You use a storage solution?

Soak the probe in the 7 for 30 min.
Rinse it.
Use the 4.0 solution and calibrate
Now the 7.0 solution and calibrate

The pen is now set, use it - Don't worry about any difference between the 2, when you calibrated.

It is calibrating to both.
 
shiva71

shiva71

Well-Known Member
Cheers, soaked it in the ph7 solution for a good while last night...if its reading the 7 as 6.5 (if i calibrate to 4) or the 4 as 4.5 (if i calibrate to 7) then surely theres something wrong?
 
OldMedUser

OldMedUser

Well-Known Member
Auto calibrating pens work by locking to the sol'n value when you push the calibrate button. If your sol'n is off, (contaminated or not properly mixed when powdered stuff is supplied), it will consider it 7 or 4 or whatever it's closest too. My 8 yo pen is usually .2 or so off when I check it but goes to 7 or 4 after calibration just fine. I keep it in storage sol'n at all times except for about 3 years where I let it dry out then soaked for 48 hours in storage sol'n before putting it back to use.

I buy the premixed calibration and storage sol'ns hoping they are right on.

:peace:
 
OldMedUser

OldMedUser

Well-Known Member
shiva71 said:
Cheers, soaked it in the ph7 solution for a good while last night...if its reading the 7 as 6.5 (if i calibrate to 4) or the 4 as 4.5 (if i calibrate to 7) then surely theres something wrong?
Click to expand...
With two-point calibration it should be able to read both at the stated value after calibration. So either you are calibrating it incorrectly, probe is faulty or your calibration sol'ns are off. I just calibrate at 7 as that's closest to what I'm looking for anyways. I'm using an ECO TestR pH1 made by Oakton/Eutech. Lost my instruction manual but it's easy enough. Rinse probe to get the storage sol'n off. Turn on then dip into pH 7 until it reads and if off the mark push Cal button and wait until it locks, (30 sec blinking), then hit Hold/Ent to finish the calibration.
 
shiva71

shiva71

Well-Known Member
Cheers OMU. Calibration fluid is fine, my other one reads them correctly. I've emailed them but no response yet. I'm possibly not calibrating correctly but it's so simple it's unlikely. In the meantime I'll have to use my bluelab but that takes 10 minutes to stabilise.
 
Dr. Who

Dr. Who

Well-Known Member
shiva71 said:
Cheers OMU. Calibration fluid is fine, my other one reads them correctly. I've emailed them but no response yet. I'm possibly not calibrating correctly but it's so simple it's unlikely. In the meantime I'll have to use my bluelab but that takes 10 minutes to stabilise.
Click to expand...

Bad probe

This is my go to liquid pH pen (for home gardening).. Tough as nails and lasts!
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Good stuff
 
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downhill21

downhill21

Well-Known Member
MickFoster said:
No brainer, needs no calibration, no calibration solutions, no storage solution, and it's never wrong.
Been using them for over 25 years.
View attachment 4477361
Click to expand...
I have to use this currently, as my pen probe died n will be 2 weeks before I have a decent one. The prob with this, is when your Rez water is no longer clear. This isn’t practical if there are dark nutes in the Rez.
 
OldMedUser

OldMedUser

Well-Known Member
Trying to find a pic but I have some pH strips I got from a place I worked 30 years ago. They have 4 coloured bars on each strip and a chart. Doesn't matter what colour your liquid is and they are really accurate but only to about 0.5. I've seen similar ones on Amazon.

Edit: Found the pic.

PhTestStrips.jpg
 
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L

LinguaPeel

Well-Known Member
MickFoster said:
No brainer, needs no calibration, no calibration solutions, no storage solution, and it's never wrong.
Been using them for over 25 years.
View attachment 4477361
Click to expand...
I used an expensive meter to check the test sample in one of those vials one day. Got a different reading every time. Poured the same sample into a regular graduated cylinder and got a consistent reading.

Could've been calcium deposit in the vial, maybe cheeseburger grease splashed out of my dirty dishes, who knows, I'm too lazy and judgemental to repeat experiments but I swear every sample I left in one of those plastic ph vials creeps up over time, yet doesn't in a graduate cylinder. 4.5-4.9mL/3 drops
 
MickFoster

MickFoster

Well-Known Member
LinguaPeel said:
I used an expensive meter to check the test sample in one of those vials one day. Got a different reading every time. Poured the same sample into a regular graduated cylinder and got a consistent reading.

Could've been calcium deposit in the vial, maybe cheeseburger grease splashed out of my dirty dishes, who knows, I'm too lazy and judgemental to repeat experiments but I swear every sample I left in one of those plastic ph vials creeps up over time, yet doesn't in a graduate cylinder. 4.5-4.9mL/3 drops
Click to expand...
I like that idea......a graduated color vial would be a lot easier than trying to match a color on a label. I know they have them for pools but it's not the desired pH range.
Did you get that separately or did it come with a test kit? I like the GH stuff so being able to get one separately would be good.
Thanks.
 
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