Oxidation-reduction potential (ORP) is a critical parameter in hydroponic systems, influencing plant growth and nutrient availability¹.

Understanding the optimal ORP range for hydroponic plants is essential for maintaining healthy growth conditions². 

Typically, ORP values between +300 mV to +400 mV³ are ideal for promoting oxygen availability and nutrient uptake in hydroponic environments. 

Introduction

ORP measurement is integral to hydroponic agriculture, where plants grow in nutrient-rich water solutions instead of soil. It is essential for understanding the oxidative and reductive properties of the solution, which affect oxygen⁴ and nutrients availability. ORP levels influence the availability of oxygen and nutrients in hydroponic systems, directly impacting plant health and growth⁵.

Maintaining optimal ORP conditions is essential for maximizing nutrient uptake and promoting vigorous plant growth in hydroponic setups.

The optimal ORP range for hydroponic plants varies depending on factors* such as plant species, growth stage, and environmental conditions. Generally, ORP values between +300 mV to +400 mV⁶ are conducive to healthy plant growth in hydroponic systems. 

Deviations from this range can affect nutrient availability and oxygen levels, potentially compromising plant health and productivity.

Method

Collection & Preparation

1. Collect water samples from the hydroponic solution reservoir, ensuring representative sampling from different areas of the system.
2. Prepare the ORP meter for measurement, ensuring proper calibration.   

Calibration

Calibrate the LAQUAtwin ORP-11 pocket meter using 225 mV standard solution to ensure accurate readings.

Measurement

1. Submerge the ORP sensor into the hydroponic solution and allow the reading to stabilize.
2. Record the stabilized ORP reading displayed on the meter, ensuring consistent measurement technique across samples.

ORP measurement helps hydroponic growers to fine-tune the nutrient solution, ensuring plants receive the optimal balance of nutrients and oxygen for healthy growth and maximum yields.

Regular ORP monitoring allows for early detection of potential problems such as nutrient deficiencies or oxygen depletion. Growers can take timely corrective actions to maintain ideal growing conditions.

By using the LAQUAtwin ORP-11 pocket meter, growers can maintain precise control over ORP levels, leading to consistent and robust plant growth in hydroponic system.

Table 2. Follow Up Actions to Increase or Decrease ORP (Oxygen Level)

References and Suggested Readings

Revision 0, 3 March 2025