Hydroponics for Hackers: Automated NFT Systems You Can Build

In hydroponics, NFT stands for nutrient film technique — and no, this is not an article about JPEGs. It’s one of the simplest, most hackable ways to grow food without soil: a pump pushes a thin film of nutrient solution down a sloped channel, past bare roots, and back into a reservoir. No grow medium, no watering schedules, just flow.

Why NFT wins for tinkerers

• No growing medium — roots hang in air, which means they get oxygen constantly.
• Recirculating loop — a 10-litre reservoir can feed dozens of plants.
• Fast crops — lettuce, basil, spinach and kale go from seed to harvest in 4–6 weeks.
• Tiny footprint — one channel of 4 plants fits on a bench or windowsill.

The parts list (NZ edition)

• Channels: 100 mm square guttering or PVC downpipe from Mitre 10 or Bunnings. Drill 50 mm holes every 200 mm with a hole saw, and slope the channel 1:30.
• Pump: a submersible 600–1000 L/h pump from any local hydroponics shop. Flow rate matters more than pressure — NFT roots die fast without flow.
• Reservoir: an opaque, food-grade plastic tote. Darkness is non-negotiable: algae loves clear containers.
• Controller: an ESP32 or ESP8266 running ESPHome or Tasmota. This is the heart of the automation.

Sensors that actually matter

• EC (electrical conductivity) — measures nutrient strength. A $30 TDS/EC pen is fine to start; step up to an Atlas Scientific probe when you want continuous logging.
• pH — target 5.5–6.5 for leafy greens. pH drifts upward as plants take up nutrients, so plan for correction.
• Water temperature — keep it below 22–24 °C. Warm reservoirs breed root rot (Pythium), which is the number one NFT killer.

Automation that helps, in order of priority

1. Pump timer — 15 minutes on, 15 off. Add a failsafe so the pump stays on if the timer dies: NFT roots can suffer in under an hour without flow.
2. pH dosing — peristaltic pumps with food-grade pH-down (citric acid) and pH-up. Dose in tiny pulses.
3. EC top-up — when EC drops, add nutrient concentrate; when it climbs, add plain water. This alone fixes most “why is everything yellow” problems.
4. Alerts — push pH and EC readings to Home Assistant or Telegram and only intervene when something drifts.

sensor:
  - platform: atlas_ph
    name: "Reservoir pH"
    update_interval: 60s

The two mistakes everyone makes

• Chasing perfect pH instead of stability. Plants tolerate slow drift; they hate swings. A stable 6.8 beats a wobbling 6.0.
• Overfeeding. Start greens at EC 1.0–1.4 mS/cm. Most “nutrient burn” is too much, not too little.

The NZ reality check

• Power: a pump and LED bar cost a few dollars a week to run. In winter a small reservoir heater costs more than the lights — insulate the tote first.
• Climate: in summer, shade cloth and airflow matter more than nutrients; in winter, wrap the reservoir so the roots stay above 15 °C.
• Suppliers: local hydroponics shops beat overseas shipping on nutrients, and bulk salts (Masterblend-style mixes) are genuinely cheap.

Start with one channel of lettuce and let the sensors do the worrying. Four weeks later you’ll have a salad you grew with a YAML file — and that’s the whole point.