Day 36 / Week 6
Issues, Solutions & Defoliation Log
1. Issues & Root Causes:
Acute Ca/Mg Lockout ("Formula 1" Effect): Pushing metabolism to the absolute redline (DLI 55, CO₂ 1200 ppm, 29°C) triggered a severe root zone acidification down to pH 5.5 alongside high EC (2.5). Heavy potassium cation competition combined with acidic media blocked calcium and magnesium uptake, causing necrotic rust spots on the leaves within 4 hours.
*Dehumidifier Failure: The 12L dehumidifier was overwhelmed by peak transpiration from four mature plants in coco, dropping air and Leaf-VPD well below safe thresholds and stalling the transpirational pull.
2. Implemented Solutions:
Substrate Reset & Buffering:** Flushed the pots with an input EC of 1.5–1.9 mS/cm cut with tap water to introduce a natural bicarbonate buffer. Runoff stabilized right inside the ideal target window for bloom: pH 6.1–6.3 and EC 2.2–2.4 mS/cm
Climate Recovery (30L Dehumidifier Upgrade): Installed a heavy-duty 30L unit, bringing humidity down to ~54% and holding air VPD at 1.44–1.50 kPa, which delivers an ideal Leaf-VPD of ~1.25–1.35 kPa
Light Intensity Relief: Dialed PPFD down to ~520 µmol/m²/s (DLI ~37 mol/m²/d) to halt photo-oxidation of damaged leaf tissue and allow vascular recovery.
3. Defoliation & Lollipopping:
Under-Canopy Strip: Stripped the entire lower third of foliage directly up to the trellis net line.
Pruning Non-Productive Growth:** Cleaned out all shaded popcorn/larf bud sites and removed necrotic leaves damaged during the lockout.
Airflow Tunnel Established:** Created an open air channel underneath the canopy and around the elevated fabric pots, preventing stagnant humidity pockets and redirecting full hydraulic pressure to the primary top colas.
Day 38
Netafim bow instaled.
Day 39
Mastered pH stability. It was dificult but now runoff are pH 6.1 ec 3.5
No lockouts. Happy
Day 42
Swapped out the empty CO2 bottle today after running dry on Day 41. Dialing in relative humidity and VPD in a fully sealed room has been quite a challenge, but parameters are finally locked in: temperatures consistently above 28°C and VPD rock-steady at 1.4 kPa. Really hoping it stays this stable now, as constant swings in humidity and VPD are far from ideal for the plants. Just hoping no other equipment dies on me like the dehumidifier did 6 days ago! Canopy is looking strong and ready for peak flowering.
Netabow watering a great.