Deron Caplan + CannaCribs
Mar 27, 2025
Analyzing Runoff with the Pour-Through Method: Cannabis Cultivation
In this instructional video, Deron Caplan introduces the pour-through method as a practical way for cannabis cultivators to monitor electrical conductivity (EC) and pH directly in the root zone. He emphasizes that understanding root-zone conditions is central to irrigation and fertigation management, since what the plant actually receives often differs from the feed solution being applied.
The pour-through technique begins with fully irrigating the plant using the current fertilizer solution until saturation and runoff occur. After waiting 30 minutes to 2 hours—allowing the root-zone solution to reach equilibrium—the grower displaces a small portion of that internal solution. This is achieved by slowly applying measured increments of the same fertilizer solution on top of the substrate. For a 2.2-gallon pot, Caplan uses 100 mL increments, waiting 2–5 minutes between pours until 50–100 mL of displaced liquid collects in the saucer below. He stresses the importance of not exceeding this range, since over-dilution skews readings.
To prevent contamination, the pot is elevated above the saucer, ensuring liquid flows out without being reabsorbed. Multiple plants across a bench should be sampled for representative results, rather than testing a single container. The sample is then measured with calibrated EC and pH pens, which must be regularly cleaned and verified with distilled or reverse-osmosis water to maintain accuracy.
Caplan records example readings of EC 4.1 and pH 6.0, both within acceptable ranges. He notes that consistency between crops matters more than exact technique variations, citing North Carolina State University’s foundational work on the method. Tracking these values week by week enables growers to see how conditions shift across the cultivation cycle and adjust fertigation strategies accordingly.
He contrasts pour-through testing with measuring bulk runoff collected from trays, which often provides misleading data. Tray runoff reflects dilution from overwatering and multiple plants, obscuring the actual environment surrounding roots. In contrast, the pour-through approach displaces water already equilibrated in the substrate, yielding a more accurate picture of what plants are experiencing.
By adopting this method, cultivators can set and maintain target EC and pH levels in the root zone, refine irrigation strategies, and ultimately improve crop consistency and performance. For commercial cannabis operations, this represents a cost-effective, repeatable, and scientifically grounded tool for precision horticulture.