PPM/EC meters How to and how not to, from experience.

Adam1303

Member
Hello,

I'm quite the newbie myself, but having made this mistake myself I figured I'd write this so I can help as many people as possible avoid the situation I put myself in.

I bought myself an EC meter which displayed as PPM, little did I know that depending where you live different formats of PPM are used. From what I've read America uses x700 PPM where as EU mainly uses x500, which will impact your readings when converting into EC on a MASSIVE scale and potentially lead to severe nute burns if the problem isn't recognized fast enough and treated.

I strongly suggest when buying or after buying an EC meter you read the instructions, just so you're aware what readings it takes (either x500 or x700) I didn't know about the different readings, so when it came to adding nutes I was baffled when I noticed nute burn.

EC is calculated by dividing the PPM by either 500 or 700, depending on what your meter reads.. This mightn't sound like an issue, but look at the example below and you'll see why it could lead to a problem on a large and VERY costly scale.

For examples sake we'll say that your EC meter is displaying PPM of 700
x500 meter readings would be 700/500 which would give you an EC of 1.4 where as the x700 reading would be 700/700 which would give you a EC of 1.

This doesn't really look like a huge issue but if you're following recommended ECs either from an experienced grower or perhaps even a website and you're unaware of what format your meter reads in, it could potentially lead to you either burning your plants or in some situations lead to a deficiency.. Either of which aren't too pleasant and can leave newbies like us quite stumped and deterred, a situation and feelings I know all too well now.

Here's a small chart to help out if it's needed
PPM ec x 700
140 = 0.2
280= 0.4
420= 0.6
560= 0.8
700= 1.0
840= 1.2
980= 1.4
1120=1.6
PPM ec x 500
100= 0.2
200= 0.4
300= 0.6
400= 0.8
500= 1.0
600= 1.2
700= 1.4
800= 1.6

This mightn't be news to a lot of people, but I hope it does help some people.

Regards and best wishes,

Adam.
 
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