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Sensor Comparison.
Sensor Comparison
Pick the right sensor for your build. Spec, accuracy, price, OAT/MQTT compatibility across temp, humidity, CO₂, pH, EC, PAR.
How to choose a sensor
| Need | Recommendation |
|---|---|
| Cheap temp/humidity in tent | BME280 ($5) or DHT22 ($6) — both work |
| Reliable temp/humidity for grow room | BME280 — better accuracy than DHT22, similar price |
| Outdoor wireless temp/humidity | Govee H5074 BLE ($15) — battery-powered, no wiring |
| Cooler / freezer temp probe | DS18B20 waterproof ($3) — long cable runs OK |
| Real CO₂ measurement | SCD40 NDIR ($55) — true CO₂; Senseair S8 ($45) alt |
| Cheap "CO₂" indicator (don't buy) | MH-Z19 reads CO₂ but variability is poor — invest in NDIR |
| Hydroponic pH | Atlas Scientific pH probe + circuit ($75) for accuracy; Bluelab probe ($90) |
| Hydroponic EC | Atlas Scientific EC probe + circuit ($95) |
| Soil moisture (capacitive) | Capacitive soil moisture sensor v1.2 ($3) — good enough for indoor |
| Soil moisture (lab-grade) | Decagon EC-5 / TEROS 12 ($150-300) — for research |
| BLE soil sensors | Mi Flora ($10-15) — BLE outdoor; battery 12 months |
| PAR (quantum) | Apogee SQ-500 series ($250+) — research-grade; cheaper LI-COR alternatives exist |
| Weight (beehive / plant scale) | HX711 + 50kg load cells ($15-25) — DIY scale |
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