Measuring & Control — EC Meters

An EC meter counts salts, not a recipe. Two very different mixes can give the same EC, so the number tells you how much is in your water and not what. That makes the choice here a practical one: which unit you read in, where you measure, and whether the instrument stays put or you pick it up.

EC and ppm are not the same number

Some meters show ppm or TDS instead of EC. That is a converted value, and the conversion factor used differs between manufacturers, so one brand's ppm does not equal another's. If you follow a feed chart, record in EC and set your meter to it. The Bluelab EC pen lets you choose between the two, Milwaukee's EC60 shows conductivity, TDS and temperature, and the MW806 Max adds pH to that.

In the tank, in the pot or continuously

The Bluelab Pulse reads EC, moisture content and temperature straight from the substrate and sends it to your phone. That is a different measurement from the one on your feed water, and usually the more interesting one, because that is where the plant is. If you mainly want to measure in the medium, look at Soil Meters as well. Milwaukee's MC310 hangs permanently in the reservoir, and the EC40 is a waterproof 42 cm probe stick that stays in the tank and needs no calibration.

Range and format

The Bluelab Truncheon in its standard version reads from 0.2 to 3.6 EC, the range most feed charts operate in. For a pocket there is Milwaukee's C66 with an IP65 rating and the CD611 from the budget line; the MW302 is the portable from the Standard line and also sits in the case alongside the MW710 and MW100, calibration fluid included. If you are testing pH from the same bucket anyway, the Bluelab Combo and Combo meter Plus, Milwaukee's MC811 Max and MW806 Max, the Guardian Wifi and the AC Infinity Hydroponic Meter PRO Kit read both at once, and they are under Combo Meters.

Frequently asked questions

Does an EC meter need calibrating too?
Most do, with EC 1.413 as the common standard and 2.77 for the Bluelab kits. The EC40 probe stick is the exception on this page. Everything you need for it is under Calibration Fluids.

Can I compare readings from two brands of meter?
In EC yes, in ppm not without care, because the conversion differs by brand. Record your readings in EC, even if your meter can display something else.

My tank is deep. Which meter suits that?
A probe stick or a monitor that stays in it. With a pocket meter you scoop a sample, and then you are reading what sat at the top rather than what your pump picks up.