Hey everyone,
I’m running a coco grow and I’m a bit confused about my runoff EC behavior.
Setup / parameters:
Medium: Coco
Feed EC: 1.9 Feed pH: 5.7
Runoff EC: 3.5–4.3 (first runoff of the day sometimes ~4.4, then dropping) Runoff pH: ~5.1
Irrigation strategy:
~6 irrigation events in the morning to reach runoff (~50% runoff) Then ~6 more events spread throughout the day Final event shortly before lights off
Goal: keep overnight dryback low (~10–15%)
Environment:
Day: 27.5°C, 55–60% RH Night VPD: ~0.7 Day VPD: ~1.0
Currently on the first day of week 6 of flower
Observations:
Plants look very healthy, one of 3 with very little signs of tip burn, no other deficiency
Runoff EC is always high, especially first runoff in the morning
EC drops gradually during the day but stays elevated overall
I’m getting plenty of runoff (around 3–4L total across 3 plants daily)
My question:
Why is my runoff EC still so high despite: -consistent feeding at 1.9 EC -significant daily runoff -relatively low dryback overnight
Is this just normal salt accumulation in coco under high-frequency fertigation, or does it indicate hidden buildup in the root zone?