Accuracy of PPM meters help

[New2It]

Sorry, not sure where to post this, but looking for thoughts on PPM meters. I got a vivosun one to begin, then just got another one for shits and giggles... I'm kind of weird about things not giving me accurate readings. So, in my tap water they read within 5-10 of each other, in distilled water they're dead on, then in my runoff they are WAY different.... that concerns me. What should I do? which one do I trust? Please and thank you

 

[neneboob]

It sounds like you need to calibrate them.

 

[Grownsince95]

Sorry, not sure where to post this, but looking for thoughts on PPM meters. I got a vivosun one to begin, then just got another one for shits and giggles... I'm kind of weird about things not giving me accurate readings. So, in my tap water they read within 5-10 of each other, in distilled water they're dead on, then in my runoff they are WAY different.... that concerns me. What should I do? which one do I trust? Please and thank youView attachment 2467191

Is the one reading higher in the runoff also reading higher in the tap water and vice versa? Or is it random?

 

[Jmaes Mabley]

Have they been calibrated?

 

[New2It]

It sounds like you need to calibrate them.

Not sure how to do that. Nowhere in the stuff they came with is calibration mentioned....I had the same thought, I calibrate my ph meter every time.

 

[New2It]

Is the one reading higher in the runoff also reading higher in the tap water and vice versa? Or is it random?

It is the same one reading higher in both.

 

[orggrwr]

Went through the same thing when I started growing. Throw those cheap meters away and get an Apera or a Blue Lab. The first meter I bought was Vivosun and you could test the same sample 5 times and get 5 totally different answers. I prefer the Apera but a lot of people swear by blue lab. Although I grow with living soil now so haven't had to worry about ph or ppm for a while.

 

[ArtfulCodger]

Any chance one is set to read PPM700 and the other is PPM500? That could account for it.

 

[JIMKSI64]

The Vivosun box set and my lack of identifying PH related issues killed my first 2 plants.

EC/ppm tools need calibration. The fluid needed is NOT standardized. You will need to research your tool to see what you need. 2 different tools may need different solutions.

Also FYI. Not optional. Calibrate your tools for pH and EC/ppm. Write down everything. I can not stress this enough about writing down trends in your grow.
A lot of guys get into a rut where they pour the same nutes in the same amount of water and for 6 nute mixes they all tested right at 6.3 or whatever but then you do the same thing on number 7 and it appears to be low so you add more up.
You did the same thing and got a different result? So you adjusted it? When you track ins and outs you would recognize the tool may be the culprit.

 

[Grownsince95]

Any chance one is set to read PPM700 and the other is PPM500? That could account for it.

There's your answer. The math even checks out. The higher reading is for ppm/700.

 

[New2It]

Any chance one is set to read PPM700 and the other is PPM500? That could account for it.

I have no idea. Possibly. I didn't realize that was a thing

 

[New2It]

There's your answer. The math even checks out. The higher reading is for ppm/700.

How and why would there be different settings or whatever? Isn't it a straightforward sort of thing? So quite possibly I've been doing this wrong the whole time? This begins to suck dude. I just want stuff that works properly

 

[NairnM16]

How and why would there be different settings or whatever? Isn't it a straightforward sort of thing? So quite possibly I've been doing this wrong the whole time? This begins to suck dude. I just want stuff that works properly

Blue labs are solid I’ve had good readings from mine for about 3 years before needing to calibrate and at tht it was a 2 step process they send everything u need with the unit, I’ve got the wall mounted ones but the handheld are just as reliable

 

[New2It]

The Vivosun box set and my lack of identifying PH related issues killed my first 2 plants.

EC/ppm tools need calibration. The fluid needed is NOT standardized. You will need to research your tool to see what you need. 2 different tools may need different solutions.

Also FYI. Not optional. Calibrate your tools for pH and EC/ppm. Write down everything. I can not stress this enough about writing down trends in your grow.
A lot of guys get into a rut where they pour the same nutes in the same amount of water and for 6 nute mixes they all tested right at 6.3 or whatever but then you do the same thing on number 7 and it appears to be low so you add more up.
You did the same thing and got a different result? So you adjusted it? When you track ins and outs you would recognize the tool may be the culprit.

I have been tracking my numbers and amounts of what I use. They seem to be staying pretty consistent as far as the readings go, I've just had some concern about accuracy and now I have even more concern with 2 different readings. Now it just sounds like everything has been wrong possibly both grows and I'm almost over it. Sorry for my poor attitude, this has been frustrating... thank you for your help

 

[NairnM16]

How and why would there be different settings or whatever? Isn't it a straightforward sort of thing? So quite possibly I've been doing this wrong the whole time? This begins to suck dude. I just want stuff that works properly

You get different reading depending on what the pen is showing

Ec = 1.0
Tds would be 1.0x500 =500tds
Ppm would be 1.0 x 700 = 700ppm

All the same thing just different measurements

I blame the Us for using anything but the metric system

 

[New2It]

You get different reading depending on what the pen is showing

Ec = 1.0
Tds would be 1.0x500 =500tds
Ppm would be 1.0 x 700 = 700ppm

All the same thing just different measurements

I blame the Us for using anything but the metric system

Thank you. That makes sense. But both say they're reading ppm

 

[Grownsince95]

Thank you. That makes sense. But both say they're reading ppm

They are both reading ppm. EC is the universal scale. 700 uses KCL and 500 uses NACL as their "assumed" salt. Most nute brands will tell you which one to use or just stick with EC because both of the different numbers on your pen equal the same EC.

 

[JIMKSI64]

Much like a ruler that measures in 1/8 inch vrs 1/4 inch the scale of 700 is more accurate although no more precise than the 500 scale.
And yes English measurements are just silly. Metric makes sense.

 

[Ninjadogma]

I just came up with an idea for a good side hustle. There's a guy who sharpens clipper blades for pet trimmers and he announces when he's going to be at a particular store and people show up to get their clipper blades sharpened.

So a similar idea would to stock up on the standard solutions and deionized water and show up at a nursery on a Saturday to calibrate those pH and EC pens for $5 a pop.

 

[New2It]

I just came up with an idea for a good side hustle. There's a guy who sharpens clipper blades for pet trimmers and he announces when he's going to be at a particular store and people show up to get their clipper blades sharpened.

So a similar idea would to stock up on the standard solutions and deionized water and show up at a nursery on a Saturday to calibrate those pH and EC pens for $5 a pop.

Lol, for sure. It's definitely a racket of some sort... you telling me we don't have the technology to make these things work, or to make a solution that has a decent shelf life? We send information through invisible waves in the air and we can't figure this shit out? Lol, it's crazy