pH decides whether your plants can use the feed you bought. EC tells you how strong that feed is. You need to know both, and you need a meter you can trust. An uncalibrated pH pen is worse than no pen at all, because it gives you confident wrong numbers and you act on them.
Which meter do you actually need?
| If you... | Buy | On the shelf |
|---|---|---|
| Hand water and just need pH | pH pen | Bluelab pH Pen, Aqua Master P50 Pro, Hydro Axis pH Meter |
| Want to check feed strength | EC pen | Bluelab EC Pen, Bluelab Truncheon, HM Digital COM-100 |
| Want pH and EC in one tool | Combo pen or meter | Aqua Master P110 Pro 2, Bluelab One Pen, Bluelab Combo Meter |
| Run a reservoir 24/7 (DWC, NFT, drip) | Guardian-style monitor | Bluelab Guardian Monitor Wifi, Aqua Master W650 |
| Want to read the root zone itself | Substrate or soil meter | Bluelab Soil pH Pen, Aqua Master S300, Bluelab Pulse |
Calibration in 30 seconds
- Calibrate pH against 4.0 and 7.0 solutions, monthly at minimum, weekly if you grow seriously. We stock Bluelab pH 4, Bluelab pH 7 and Flairform buffers.
- Check EC against a standard such as Bluelab 2.77 EC or Aqua Master EC 1413.
- Store the pH probe wet in storage solution. Never dry, never in distilled water.
Need pH Up or Down? That lives in pH Up and Down. For target numbers by stage, see the feeding guide.
pH and EC meter questions
Do I need a pH meter and an EC meter?
If you feed with liquid nutrients, yes. pH tells you whether the roots can take up the feed. EC tells you how strong it is. A combo pen like the Aqua Master P110 Pro 2 or Bluelab One Pen does both in one tool.
How often should I calibrate my pH pen?
Monthly at minimum, weekly if you are feeding every day. Use 7.0 then 4.0 calibration solution and keep the probe wet in storage solution between uses. A probe that will not hold calibration needs replacing, which is why we stock replacement probes.
Should I read EC or PPM?
EC. PPM is a conversion and there are 3 different scales. EC 2.0 reads as 1,000 PPM on the 500 scale and 1,400 PPM on the 700 scale, so PPM advice from the internet is often wrong for your meter. Australian feed charts use EC.
Pen or Guardian monitor?
Hand watering pots? A pen is all you need. Running a reservoir that sits for days, like DWC or a recirculating system? A monitor such as the Bluelab Guardian watches pH, EC and temperature around the clock, so you catch drift before your plants do.
