A Practical Guide to Measuring pH and EC in Soil and Container Plants
In container growing, healthy plants depend on more than the feed you mix. As water moves through the soil or substrate, plants take up ions, water content shifts, and salts can accumulate or leach away. Measuring the input alone does not show what is available around the roots.
The pour-through method helps growers understand this root zone environment without disturbing the plant, giving practical insight into pH and EC while the crop is still growing.
What the Pour-Through Method Measures
The pour-through method collects leachate, the solution that drains from the bottom of a container after irrigation. This leachate represents:
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the nutrient concentration in the root zone solution
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the pH environment experienced by the roots
Unlike slurry testing, which dilutes the sample, pour-through captures solution that has already interacted with the substrate and plant. From that leachate, growers measure:
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pH
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EC (electrical conductivity)
The Pour-Through Method results tend to align closely with the saturated media extract (SME), the standard used in laboratory analysis.
How to Perform a Pour-Through Test
Step 1: Irrigate Normally
Water the plant as you typically would. The substrate should be at or near container capacity.
Step 2: Wait
Allow time for the solution to stabilise in the root zone. This is typically around 30 to 60 minutes, depending on irrigation and substrate conditions.
Step 3: Apply a Measured Volume of Water
Add a small, consistent amount of distilled water to the top of the container. This pushes existing solution downward.
Step 4: Collect Leachate
Capture 50 milliliters of the liquid that drains from the bottom using a clean container or saucer.
Step 5: Measure
Measure pH and EC directly in the collected leachate. Note: No filtration or additional preparation is required.
Accurate pour-through testing depends on measuring pH and EC reliably. 👉 Explore Bluelab Pens
Interpreting Pour-Through Results
Pour-through results are useful because they capture leachate from the root zone, giving growers another way to monitor pH and EC in container-grown crops.
pH
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Typically aligns closely with SME values
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Most crops perform well in the 5.5 to 6.5 range depending on the plant
Conductivity
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A common working range for many container-grown crops is 1.5 to 3.5 mS/cm, although this varies depending on crop type and growth stage
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Higher values may indicate salt build-up
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Lower values may indicate underfeeding or excessive leaching
Because results are close to lab standards, they can often be compared more directly to published crop guidelines.
This makes pour-through one of the closest field methods to root zone solution analysis, often used as a proxy for saturated media extract (SME). 
Why Pour-Through is Widely Used in Container Growing
The method was originally developed in greenhouse systems and is now widely adopted across nursery, hydroponic-adjacent, and protected cropping environments.
It is valued because it provides a non-destructive, repeatable way to monitor root zone conditions.
Key advantages:
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No need to remove or disturb the plant
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Captures leachate from the root zone without requiring a soil extract
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Can be repeated frequently on the same crop
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Results are often within 0.2 to 0.4 pH units of lab SME values
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EC readings closely track lab-based measurements
Limitations to understand:
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Results depend on consistent irrigation practices
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Timing between irrigation and sampling affects readings
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Slow-release fertilisers can influence readings unpredictably
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Less suitable for open-field soil growing where leachate cannot be collected
What Pour-Through Tells You That Other Methods Don't
Each testing method answers a slightly different question. Pour-through is particularly useful because it shows:
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what the root zone solution looks like after irrigation
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how feeding and irrigation practices are affecting pH and EC
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whether salts are accumulating over time
Compared to other approaches, pour-through shows mobile solution chemistry at the root interface. This makes it especially valuable for growers managing fertigation programs.
If you are comparing different testing approaches, you can also explore:
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Soil slurry testing for baseline analysis. Read more: https://eu.bluelab.com/blogs/articles/soil-slurry-testing
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Direct measurement for real-time monitoring. Read more: https://eu.bluelab.com/blogs/articles/direct-soil-measurement
When Should You Use the Pour-Through Method?
Pour-through works best as part of a regular monitoring routine, especially in container-grown crops where root zone conditions can change quickly.
It is particularly useful for:
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greenhouse and nursery production
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container-grown crops and potted plants
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managing fertigation programs
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diagnosing nutrient imbalances
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tracking EC build-up over time
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verifying that feeding strategies are working as intended
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growers who need a non-destructive testing method
It is less suited to open field soil systems, casual one-off testing, or situations where irrigation is inconsistent.
Consistency turns pour-through from a rough check into a powerful monitoring tool.
Measuring Accurately with Bluelab
Because pour-through relies on liquid measurement, the quality of your readings depends on how easily and accurately you can measure pH and EC in solution.
Growers need tools that:
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stabilise quickly in nutrient solutions
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handle repeated testing without drift
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are waterproof and robust enough for daily use
Bluelab tools are designed for this type of workflow.
The Bluelab OnePen measures both pH and EC in a single device, making it ideal for pour-through testing where both values are needed at the same time.
For growers using separate tools:
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The Bluelab pH PenPlus measures pH and temperature accurately in solution and is designed for reliable, repeatable testing
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The Bluelab Conductivity Pen measures EC and temperature in leachate
Pour-through testing, also known as leachate testing, adds another layer of insight rather than replacing other methods.
By measuring leachate from the root zone, growers gain another way to understand how water, nutrients, and substrate interact. Over time, that insight makes it easier to adjust feeding, prevent salt build-up, and maintain a more stable growing environment.
