PPM meter hassles

[shiva71]

Hiya
I have 2 pens - an Adwa ad31 and a Milwaukee ec59, both costing around €50, not top notch gear but should be good enough.
Every day i check with my 1413 calibration solution, both are always out by as much as 200. I calibrate, turn off/on, check again, they are always both out by less. After 3 or 4 calibrations they read the solution ok. Next day, rinse and repeat. I have to do this every time i want to check my rez ppm.
Whats going on? Am i doing something wrong? Or do i just have two shite products?
Thanks!!

 

[Roger A. Shrubber]

you should not have to calibrate every day, once a month should be more than sufficient.
maybe your calibration fluid has gotten contaminated? if they're both reading the same amount over seems like it might be the solution and not the meters.
it is odd that they come into line after multiple checks...are you sure you're following the calibration instructions for both your meters?

 

[Lordhooha]

Hiya
I have 2 pens - an Adwa ad31 and a Milwaukee ec59, both costing around €50, not top notch gear but should be good enough.
Every day i check with my 1413 calibration solution, both are always out by as much as 200. I calibrate, turn off/on, check again, they are always both out by less. After 3 or 4 calibrations they read the solution ok. Next day, rinse and repeat. I have to do this every time i want to check my rez ppm.
Whats going on? Am i doing something wrong? Or do i just have two shite products?
Thanks!!

One word truncheon. Weapon, stirring stick and never stops

 

[SnidleyBluntash]

Is your calibration solution contaminated?
Are you rinsing the meter off well after each use?
Both meters acting funky is strange.

 

[Jjgrow420]

have you ever cleaned the probes?

 

[shiva71]

Thanks for replies. I think its something to do with this feckin' conversion BS. Never heard anything about this until a few weeks ago, thought 1ppm is 1ppm like 1g is 1g...seems not.
As usual i was being a cheap ass and reusing calibration solution, that wasnt helping but i have 4 x 250ml bottles now, so i think that should be ok.
I have them both set to 0.7 now and they seem more stable.
Is IPA ok to clean probes?
edit: nope. 10 mins later my 1413 solution is 1510. FFS!

 

[twentyeight.threefive]

Thanks for replies. I think its something to do with this feckin' conversion BS. Never heard anything about this until a few weeks ago, thought 1ppm is 1ppm like 1g is 1g...seems not.
As usual i was being a cheap ass and reusing calibration solution, that wasnt helping but i have 4 x 250ml bottles now, so i think that should be ok.
I have them both set to 0.7 now and they seem more stable.
Is IPA ok to clean probes?
edit: nope. 10 mins later my 1413 solution is 1510. FFS!

Don't use IPA on probes. A KCl or other type of storage solution should be used.

 

[jondamon]

Thanks for replies. I think its something to do with this feckin' conversion BS. Never heard anything about this until a few weeks ago, thought 1ppm is 1ppm like 1g is 1g...seems not.
As usual i was being a cheap ass and reusing calibration solution, that wasnt helping but i have 4 x 250ml bottles now, so i think that should be ok.
I have them both set to 0.7 now and they seem more stable.
Is IPA ok to clean probes?
edit: nope. 10 mins later my 1413 solution is 1510. FFS!

You’re throwing away the solution that your poured out for calibration right?

You’re not dumping it back into the bottle it came out of?

 

[shiva71]

You’re throwing away the solution that your poured out for calibration right?

You’re not dumping it back into the bottle it came out of?

Yeah i was, and it was pretty skanky.
And i hadnt been rinsing probes after use.
Both of which point to my probes being filthy, seems like a very possible explanation. Ill soak them overnight in KCI.
Cheers!

 

[Roger A. Shrubber]

scrub-gently-with a tooth brush under warm running water at least once a week.
the southern ag calcium nitrate i use (or have been using...)has some kind of greasy chelating agent in it, leaves a ring around the top of my water buckets, and you know if it does that, it's leaving the same shit on my meters, but even without that, all the salts and minerals dissolved in your nutrient solution are still going to build up on those surfaces over time

 

[shiva71]

scrub-gently-with a tooth brush under warm running water at least once a week.
the southern ag calcium nitrate i use (or have been using...)has some kind of greasy chelating agent in it, leaves a ring around the top of my water buckets, and you know if it does that, it's leaving the same shit on my meters, but even without that, all the salts and minerals dissolved in your nutrient solution are still going to build up on those surfaces over time

Thanks. They are buggered. Ive just sat with a pot of cal sol, tap water i know is 190ppm, and some of my rez water and readings were absolutely all over the place nothing reading the same twice despite multiple calibrations. Its just weird both of them doing the same thing, that suggests human error but i cant for the life of me figure out what im doing wrong...tried cleaning with IPA (quick search suggested its ok) but maybe need to clean a bit more...

 

[cannabineer]

Don't use IPA on probes. A KCl or other type of storage solution should be used.

EC probes are metal electrodes. A pH probe is the glass bulb that benefits from being stored in saturated aqueous KCl.
The isopropyl should be without detriment.

 

[twentyeight.threefive]

EC probes are metal electrodes. A pH probe is the glass bulb that benefits from being stored in saturated aqueous KCl.
The isopropyl should be without detriment.

Great call. For some reason I pictured all my probes as glass.

 

[SnidleyBluntash]

Ph probe needs to be stored in proper solution, TDS just rinse well immediately and it will be ok.

 

[shiva71]

The chart on the calibration solution i assume that's there for a reason? Like is says at 20° umols should be 1278, mine was 1400 at 20°...thats not right. The guy in the growshop said yeah don't worry about that...is that good advice?

 

[DCcan]

Most of the better meters will take temperature into account.
PH meters have a glass probe and a platinum coated ceramic reference probe. Black coating can be damaged turning on dry, or getting cruddy.
EC meters have 2 ceramic probes usually, reference and measuring.

Storage, Cleaning & reconditioning pH electrodes and EC Electrodes

Just some basics put together for keeping everyone green. Note that Ph meters and EC meters should be stored in different liquids, and why. Keep Your pH Electrode Hydrated: If your electrode is dry, rehydrate the sensing tip by soaking the bulb and junction in an electrode storage solution for...

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