Nutrient Solution Monitoring with Bluelab

By Deidre Hughes


A too often overlooked aspect of hydroponics is the importance of maintaining a steady and proper pH in your nutrient solution. One whole number increase or decrease in pH (ex. 6.0 to 7.0) is actually ten times either more acidic or more alkaline depending on which direction the number moves. The pH scale ranges from 0-14 with 0 being the most acidic, 7 being neutral and 14 being alkaline. Most plants thrive in a pH between 5.5 and 6.5. This is because the pH affects nutrient uptake by a plant’s roots. A lower (acidic) pH can affect the availability of Mg, P and/or Ca. On the flipside, a higher pH (alkaline) can affect the availability of micronutrients such as Fe (iron), Cu (copper), B (boron), Zn (zinc) and Mn (manganese). Certain plants have greater need for specific elements, therefore, will have a pH “preference”. Before planting a crop do proper research to determine what the needs and recommendations for your crop are. Then adjust, monitor and maintain your pH for consistent growth.

There are a number of monitors and controllers to choose from. Bluelab makes handheld meters, continuous meters and controllers for your pH. You must have one of these tools to know what adjustment should be made. Nutrient solution pH can be altered with products designed to raise or lower pH.

Leila Jones and Dustin P. Meador, Ph.D. (2019) Bluelab Grow Book (pg. 10)

Bluelab pH Pen

The Bluelab pH Pen also measures the temperature of the solution, as root health is vital to the success of a crop. Temperature affects the growth rate and structure of a plant so a solution temperature of 18 – 22˚C or 65 – 72˚F is recommended.

The handheld pH pen provides a compact quick and handy way to manage the success of your crop to ensure maximum uptake of nutrients.

Teamed with our Bluelab PPM or EC Pen, you have a handy, convenient and accurate system for ensuring optimum plant growth and health.

Bluelab pH Controller Connect

Sometimes the more you know, the better. And when it comes to managing the pH of your nutrient solution, exact knowledge makes a world of difference.

The Bluelab pH Controller Connect constantly monitors and fine-tunes the pH levels for you. But more than that, it wirelessly data logs to your computer too, putting continuous information at your fingertips in real time. Use the data to make system changes faster for the ultimate crop. You can also change the settings from your PC. Clever stuff…24 hour a day monitoring and control of your pH so you know your plants are able to get the most nutrient uptake.

Bluelab Guardian Monitor (for pH and EC)

The Bluelab Guardian Monitor Connect is not only a constant indicator of the desired levels of pH, conductivity, and temperature of your nutrient solution, it also data logs these critical parameters to your computer for you.

It does not stop there. You can access the data via the cloud from a remote mobile device or computer to check for extreme variances to ensure these critical parameters are hitting the mark for crop success.

Just one Bluelab Connect Stick is required to receive wireless data from one or more Guardian Monitor connects.

For remote or cloud access, the computer you are already data logging to will need permanent internet access.

Bluelab Combo Meter

The Bluelab Combo Meter has two probes, a Bluelab pH Probe and a Bluelab Conductivity/Temperature Probe. When taking a reading, simply place them into the solution and the selected reading is displayed on screen. As the Bluelab Combo Meter is portable and does not require a power supply to operate, it can be used anywhere, anytime to help you manage your crops’ daily nutrient requirements.


EC is also very important. EC is a measurement of electrical conductivity which is a simple reading of the dissolved fertilizers suspended in your solution. EC levels are crop dependent just like pH. For example, fruiting crops will have higher nutrient requirements than lettuce, so they will need a higher EC to meet those demands. An EC reading will not tell you the breakdown of nutrients available, but can keep you on track between lab analyses. The Bluelab Combo meter above will read EC, temperature, and pH. For EC or EC/temperature only readings you can purchase one of these products:

Bluelab Conductivity Pen (EC or ppm)

Measuring the conductivity every day is the best way to avoid over-diluting or over-concentrating your nutrient solution. The Bluelab Conductivity Pen also measures the temperature of the solution, as root health is vital to the success of a crop. Temperature affects the growth rate and structure of a plant so a solution temperature of 18 – 22˚C or 65 – 72˚F is recommended.

Bluelab Truncheon Nutrient Meter

The World’s favorite conductivity meter. Simply brilliant, brilliantly simple!

It is essential when growing with a hydroponic solution to KNOW what the strength of the solution is before feeding your plants AND while they are growing. If the conductivity reading is too low, your plants may not be getting enough nutrients. If the conductivity reading is too high, plants can dehydrate.

If you are looking for the right piece of equipment that can do it all including managing your EC and pH, take a look at the Bluelab Pro Controller Connect.

Bluelab Pro Controller

Automated, constant control of reservoir pH and nutrient levels.

Full control of reservoir pH, conductivity and temperature in one place.

When connected to a dosing system the Bluelab® Pro Controller™ manages pH, conductivity and temperature levels in reservoirs. As your plants feed, pH and nutrients are automatically adjusted to the desired range.

Monitor, data log and control your system in real time for immediate response to personalised settings and system alerts, directly from your computer. The Bluelab Pro Controller is easy to set up and includes a user friendly program to adjust your settings.

If you have question or are looking for something not on our website, please email

Download the Bluelab Grow Book here.

Happy Growing!

You can find other Bluelab products including replacement probes on our website: