Week 1 of Veg is officially in the books! It worked out perfectly that this update falls right on a Sunday. Everyone’s in weekend mode, and I actually have the time to sit down and update the diary.
What happened so far:
September 6th – The Transfer
Transferred the sprouted seedlings into the Spider Farmer DWC buckets. Each bucket was filled with 17 liters of water (exactly reaching the bottom of the net pots).
For the base water, I used RO water re-mineralized with Canna Mono CaO (1.2 ml / 5L) and MgO (0.8 ml / 5L) up to a base EC of 270 µS/cm.
You may ask why single mono-nutrients instead of premixed CalMag.
The reason is simply that I grow other plant species that require completely different Ca:Mg ratios than cannabis. Using single elements gives me total control to fix a specific deficiency (like Calcium) on the fly without unnecessarily bumping up Magnesium.
Also added Canna Aqua nutrients (Vega A+B) and Rhizotonic according to the feeding chart to hit an initial target EC of 1.2 mS/cm (1200 µS/cm). Set the initial pH to 5.5.
Substrate Choice: Pumice over Clay Pebbles
Instead of expanded clay (hydroton), I’m using pumice in the net pots. Why you ask:
Immediate Nutrient Availability: Pumice holds water and oxygen exceptionally well. The roots get immediate access to nutrients the moment they grow out of the rockwool cube—gaining a couple of crucial days before they even touch the main reservoir.
Another reason is Algae Control: Its dense structure blocks light penetration much better than clay pebbles, keeping the reservoir dark and free of algae.
Lighting & Tent Constraints
Set the Lumatek ATS 300W Pro (dimmed to 25%) at 50 cm (20") above the bucket tops, giving a PPFD of 300 µmol/m²/s.
Tent Layout Note: Space is tight inside an 80x80x180 cm setup (that's roughly 31.5" x 31.5" x 70.8" for my imperial friends).
The DWC buckets take up 40 cm (~16") of vertical space, and I expect a decent stretch (plus I'm still figuring out if 1-handed mainlining is doable! Maybe I have to change the Diary title to not-so-lazy grow).
To maximize headroom, I mounted the inline fan and carbon filter completely outside the tent so the LED can go as high as needed later on.
Daily Log & Water Chemistry:
Sept 7: pH crept up to 6.2 (expected as the pumice settles in). Adjusted back down to 5.5.
Sept 8: Minor pH drift to 6.1 → corrected to 5.5.
Sept 9: pH at 5.9 → adjusted to 5.6. Measured EC spiked slightly from 1200 to 1300 µS/cm due to minerals leaching from the washed pumice.
Top-up with re-mineralized RO water brought it right back to 1200 µS/cm. Both seedlings sitting happy at 2 cm height.
Sept 10: pH adjusted from 5.8 to 5.5. Raised the LED to 59 cm (23") above the buckets (reducing PPFD to 260 µmol/m²/s). The initial 300 PPFD kept them from stretching early on, resting at 2.5 cm (1") height.
Sept 11: Reservoir stabilized! pH held firm with no adjustments needed.
Sept 12: Small pH correction from 5.7 back down to 5.5.
Sept 13 (End of Week 1): Minor pH adjustment from 5.7 back down to 5.5. Plants are showing great progress and healthy leaf development—leaf span measured at ~5 cm (2") on Plant 1 and ~6 cm (2,4") on Plant 2. Both have a height of 3 cm (~1.2").
Ready for Week 2!