EC meter question, μS?

hey all, bought an EC meter recently and am a little confused, it reads water with three digits 000μS when in air, 405μS in water with nutes added currently. i read though heaps about EC and everyone's always talking about 0.4 etc.. with the decimal place? when i'm reading my EC do i just put a "." in front of whatever 3 numbers come up? ie if i read 405μS is that an EC of 0.405? cheers

FYI if it helps i have a TDS meter which tells me the same water with nutes is about 210ppm.

i'm a little unsure as to the accuracy of the TDS meter as i have about 15L of water in a bucket and added about 40ml of sea sole organic nutes. the bottle says 10ml (one cap) dilutes in 9L of water for plants. but 40ml of it only brought the ppm to 210 in 15L which according to most is a weak strength nute based water you would give your seedlings... it's pretty deep brown in colour (the water) so i'm wondering if there's actually plenty in there and the meter's wrong, i don't wanna over nute my plants that's all. anyway any help would be good.

darwin

Think meters, centimeters, millimeters, micrometers...

mS/cm is milliseimens per centimeter. µS/cm is microseimens per centimeter.
1mS=1000µS. 0.4 mS=405 µS

TDS requires a chemical analysis your meter can't perform. That reading is simply (mS/cm) x 500.

thanks a lot for that freezerboy, so if i'm getting a reading of 215ppm on the tds meter is that not really an accurate reading to go off alone?

mind my asking which meters you use and/or recommend? cheers mate

darwin

TDS is not Totally Dissolved Solids. Its EC times 500, 640, 650, 700, 768, 784 or a couple other numbers I can't remember anymore.

As such, your 550 solution may be stronger than my 750 solution (or not) while my 784 solution might be equal in strength to your 500 solution (unless it isn't). Because there's no standard conversion, it all goes to babel.

You can run a garden with TDS or PPM as plants are illiterate. But, until TDS and PPM are reconverted to EC where they started, they're meaningless in conversation. EC is EC wherever you go.

so probably best to stick with ec then?