The pour-through method is an extension-standard way to read the pH and EC of the solution around the roots without disturbing them. The medium is saturated, allowed to settle, then enough water is poured on to push out about 50 mL of leachate, which is measured (NC State / NCDA&CS).
In practice
Do it the same way every time, at the same time after feeding, and track the trend. Runoff EC well above input EC means salts are building up; much lower means the plant is hungry or over-leached. Runoff pH far from input pH means the medium is drifting.
Don't confuse with
- Slurry test: measures a sample of medium mixed with water.
- Root-zone flush: heavy watering to wash salts out, not a measurement.
pH measures how acidic or alkaline a solution is on a 0–14 scale; in growing it controls nutrient uptake, with soil best near 6.0–7.0 and hydro 5.5–6.5.EC (electrical conductivity) measures how well a solution conducts electricity, a proxy for total dissolved salts; growers read it in mS/cm to gauge nutrient strength.Watering to runoff means applying enough water or solution that some drains from the bottom of the container, typically 10-20% of the volume applied.Runoff EC is the conductivity of solution draining from the pot; compared with input EC, it shows whether salts are building up or being used up in the root zone.Runoff is the water or nutrient solution that drains out of the bottom of a container after irrigation; growers test it to see what is happening in the root zone.A way to measure the pH and EC of a growing medium by mixing a sample with distilled water (often 1 part medium to 2 parts water), letting it stand, and measuring the liquid.Running a large volume of low-EC water or mild solution through the medium to wash out accumulated salts; it treats the medium, not the plant, and suits any stage.
