Irrigation & Water
Water serves two purposes: feeding plants and controlling humidity. On a hot day, 90% of water usage is humidity management.
Water cost, total gallons, and average daily spend. The range is dramatic: 5 gallons on a cool cloudy day (just the morning drip cycle) to 200+ gallons on a hot dry day when misters fire 200+ pulses. At 1 to the bill. Water is the cheapest resource this greenhouse consumes.
Daily Water Consumption
Left: daily totals — the seasonal arc is visible. Winter days barely register. Spring and summer days spike with misting demand. Right: cumulative water usage over the selected period. The 200-gallon daily budget has never been a constraint.
Water Efficiency
Left: gallons per mol of DLI — are we using water efficiently relative to the available light? High values mean the misters are working overtime (hot, dry, sunny). Low values mean natural humidity is doing the work. Right: real-time flow rate from the DAE AS200U-75P water meter. Each spike is a mister pulse (~1 GPM per zone, ~1–2 gallons per 45–60 second pulse).
Mister Activity
Every mister and fog activation over the selected period. The density of this timeline tells you how hard the humidity system is working. Sparse = comfortable day. Dense wall of pulses = the misters are in a fight they can’t quite win.
Zone Distribution
Left: runtime per zone. South zone leads — it has the highest VPD (exhaust side, most sun exposure), so the firmware routes water there first. Right: mister state changes overlaid with water consumption. One zone at a time — water pressure won’t support simultaneous operation. The firmware enforces this hard constraint.
Mister Effectiveness
VPD drop per pulse by zone. South (0.15 kPa) and west (0.13 kPa) deliver real results. Center zone (0.04 kPa) severely underperforms despite 25 active nozzles — likely geometry or nozzle adjustment. Each pulse uses ~1–2 gallons of 86°F water from the Rinnai tankless heater. Warm water evaporates faster, boosting the humidity effect.
Wall Drip System
The irrigation side of water delivery. One zone covers all south + west wall shelves — cannot be software-split. Physical drip head volume restrictors allow per-plant adjustment.
| Property | Value |
|---|---|
| Coverage | South + west wall shelves |
| Schedule | Daily at 6:00 AM, 10 minutes |
| Plumbing | Dual lines — clean water + parallel fertilizer |
| Control | ESP32 relay (clean: pcf_out_1 pin 4, fert: pcf_out_2 pin 0) |
Fertigation
Every water zone has dual plumbing: clean water line + parallel fertilizer line through the fert tank. The relay selection determines whether water flows through the fert system or bypasses it. A fert master valve (pcf_out_2, pin 1) gates all fertilizer delivery — must be ON for any fert relay to flow.
| Zone | Clean Relay | Fert Relay |
|---|---|---|
| Wall drip | pcf_out_1, pin 4 | pcf_out_2, pin 0 |
| South misters | pcf_out_1, pin 3 | pcf_out_1, pin 2 |
| West misters | pcf_out_1, pin 0 | pcf_out_1, pin 1 |
Same physical nozzles/drip heads — the relay selection determines the supply path. Misters can deliver fertigation through the same heads used for humidity control.
Water Economics
| Resource | Rate | Hot Day (200 gal) | Cool Day (5 gal) |
|---|---|---|---|
| Water | $0.00484/gal | $0.97 | $0.02 |
| Gas (Rinnai heater) | marginal | ~$0.10 | ~$0.01 |
| Total | ~$1.07 | ~$0.03 |
Water is a rounding error in the daily budget. The Rinnai RE140iN tankless heater runs on demand — 140,000 BTU, 5.3 GPM capacity, far exceeding mister demand of ~1 GPM per zone.
→ See Humidity for how water translates to VPD control. → See Soil for soil moisture monitoring that will eventually drive demand-based irrigation.