EC reading confusion

[matscom]

First off the stats..
hybrid clone 80% sativa 20% indica, 6 weeks old.
24/0 in veg in coco, indoor tent with 250w light, extraction fan with fresh air intake.
temp 22°c - 27°c and RH 40% - 50%.
nutrients: canna coco a & b, cannazym and rizotonic.


Right I'm a bit stuck on the whole EC, ppm and tds thing!!
I've got a meter called HM EC-3 and it reads in ųs/cm. with a EC in its name i immediately thought it would give me it as an EC reading.

I've read a lot of info on how to convert but then its different depending on the part of the world its from (mine is usa i think). now some say that you just divide the ųs/cm reading by 1000 ? that seems too easy.

Also should i be taking the reading of my water before hand and subtract that at the end?

I've read lots of confusing charts and conversion methods and I'm baffled, what i need is for someone to sit me down and say right this is how it is...

if anyone can offer me any advice it would be greatly appreciated.

cheers

 

[Dan Ultra]

To convert µS (micro-Siemens) to mS (micro-Siemens): divide by 1000.
1000 µS = 1 mS
EC = Electrical Conductivity

This is taken from the meter site. I think you might be getting EC and PPM confused. EC is the Electrical Conductivity of the water. The more "stuff" that's in the water, the higher the conductivity will be. With your meter, if you are shooting for an EC of 1.0, your meter would display 1000µS. You would divide that number by 1000, to get to an EC of 1.0. Make sense?

PPM is Parts Per Million. IMO, PPM is more important as it gives you an easier to understand number as it displays the total "parts per million" in the water. If your water has a ppm of 80, and you add up your nutes and get appm of 480, then you have given a feeding of 400ppm.

Also should i be taking the reading of my water before hand and subtract that at the end?

With PPM, you would take the ppm of your water and subtract that from the total ppm of a feeding to get the amount of nutrients you are using.

 

[matscom]

I get it now, so lets say i have a reading of 2400us that would simply be a EC of 2.4 and if i started off with tap water at 400us (EC 0.4) it would be telling me that the level of nutrients is EC 2.0.
thanks for the help pal

 

[Weaselcracker]

If I can sneak in and ask a dumb question here?
I've yet to need my ppm meter so haven't had to sort this out yet.

If we took that ec of 2.4 for example-

On a Hannah meter which uses a .5 conversion rate: the ppm would read -1200.
On my bluelab which uses a .7 conversion rate: the ppm would read. -1680.

Correct? This is the state of things? So "ppm" is relative to what meter you're using? Or am I missing something? Thanks!

 

[cannilingus]

anything over 1000 is stout in my book. bepends on the strein. my god will take near anything. but, 1000 will be good, for anything, as well. remember., the higher the nutes, the more flushing. thats why i found a great nute line, in "dynagro" one part veg, one part bloom. use at every watering, except last two or three weeks. one good flush,and just water from then on, as needed. has all the nutes. even mg. and, i have had great results useing it.

 

[Dan Ultra]

I get it now, so lets say i have a reading of 2400us that would simply be a EC of 2.4 and if i started off with tap water at 400us (EC 0.4) it would be telling me that the level of nutrients is EC 2.0.
thanks for the help pal

exactly

 

[Weaselcracker]

Ok, but if I'm understanding things right - "ppm" isn't a reliable term to toss around because different meters apply different conversion rates to the ec - to come up with different ppm estimates....I think...lol

 

[Dan Ultra]

Ok, but if I'm understanding things right - "ppm" isn't a reliable term to toss around because different meters apply different conversion rates to the ec - to come up with different ppm estimates....I think...lol

I believe the ppm is actually the more accurate measurement and different instruments measure the conductivity differently. As long as you use the correct breakdown for your instrument, it should come to the same conclusion. i.e., you can't use the Hannah conversion rate on a Bluelab EC meter because they read the EC differently.

 

[Weaselcracker]

Thanks Dan. I'm getting more confused though now. I thought it was the ec that was written in stone. Ok I'm going to have to break down and google it now.

 

[shottafire]

You are correct that ec is what is set in stone. If you are talking to someone in terms of ppm you must state your conversion factor.

 

[Dan Ultra]

Thanks Dan. I'm getting more confused though now. I thought it was the ec that was written in stone. Ok I'm going to have to break down and google it now.

You are correct that ec is what is set in stone. If you are talking to someone in terms of ppm you must state your conversion factor.

My mistake. It all still confuses me a little as well. lol. Thanks for clearing it up shottafire!!

 

[Weaselcracker]

Ahhhh. (Big sigh of relief) thank you!

 

[shottafire]

I work at a store and it confuses most people. Its always the first question I ask when someone starts talking ppm's. Whats the conversion factor?

Once you get your feeding program/recipe figured out you can almost forget to check the conductivity alone and just make sure your ph is where you want it.

I remember when I was trying to wrap my head around ppm and ec readings when I started.... I was like WTF?

 

[matscom]

I remember when I was trying to wrap my head around ppm and ec readings when I started.... I was like WTF?

glad it wasn't just me that felt like that!
great information as always guys