confused about EC, TDS, PPM

[ukganjafarmer]

I got a "tds/ppm" meter that displays in parts per million, i thought that 1000ppm equals 1.0ec but now i think thats wrong.

Im startin a dwc the nutes i got r ionic hydro grow+bloom hard water, on the bottle it says the reccomended levels but says it in EC ms/cm wotever that means.

wots the reccommended PPM for clones?

help

 

[PuReKnOwLeDgE]

There are 3 equations a ppm meter uses to calculate. The two most common are referred to as .5 and .7 meters. Most meters use only one equation but some are switchable. You should be able to use the chart below to figure out what you have.

EC is the best way to communicate with other growers, since we all have different meters.

For clones in DWC and I speak from experience put them on .6-.7 EC.

Here is a chart, I uploaded it just for you the chart shows the 3 different meters, 0.50 / 0.64 / 0.70

 

[TwoPaid]

1000ppm on a .5 conversion meter is 2.0 EC. 500ppm is 1.0EC. 250ppm is .5 EC. If its a .7 meter then 700ppm is 1.0EC. 1400 is 2.0EC. 350ppm is .5 EC.

 

[FreezerBoy]

PPM and TDS require a chemical analysis your meter can't perform. Regardless of the name, your meter measures EC (electrical conductivity) and nothing else. Problem is, it won't display EC but rather a nonsense conversion. As an example 1.0 EC could be 500 or 640 or 650 or 700 or 768 or 784 or a couple other PPM numbers I no longer remember. Do yourself and the hobby a favor, stick to EC.

EC is measured in seimens ("wotever that means") Most commonly mS/cm or milliseimens per centimeter; Sometimes in µS/cm or microseimens per centimeter. 1mS/cm=1000µS/cm just as 1 meter=1000 millimeters. As an example 1473µS=1.5mS.

I've never bothered measuring my clone EC. I use 1/4 tsp per gallon each of GH FloraMicro and FloraBloom at pH5.8

 

[ShroomDr]

the short answer is... your 'ppm meter' doesn't measure parts per million, it actually measures electrical conductivity (ec). Your meter then uses a (superfluous) conversion to something they label 'ppm'. What they label 'ppm' has nothing to do with actual 'elemental ppm', its just what they named there conversion.

Different manufactures use different scales to convert the 'ec' to 'ppm' but again, this is just labeled 'ppm' its not a measure of parts per million. (they should have called it anything other than 'ppm'. labeling the conversion 'hamburgers' would have made more sense.)

Do yourself a favor, and just forget about the 'ppm' conversion(s) and learn 'ec'. Most growers start at 0.8-1.0ec, then work upto 1.7-2.2ec, some strains can take 3.1+

 

[SnowGro]

Good clear description of an important topic.
Sticky imho.

 

[ukganjafarmer]

Thank you all!

 

[ShroomDr]

My old AK47 could take up to 2170 hamburgers, but she really only needed 1540 hamburgers to be perfectly healthy.

 

[BLUNToPOTomuss]

Sticky this! Very informative, Ive been wondering the difference of EC,PPM,TDS for a while now!

Thanks for the clearification!!!

 

[PuReKnOwLeDgE]

Glad it is helping some understand how they all corollate. It took me a while myself when first starting to learn.