What size, and what it costs.
A chiller that is forty per cent undersized does not hold the reservoir forty per cent less well. It holds it at 27 °C all summer, which is not a degraded outcome — it is root disease. So the sizing is arithmetic from stated assumptions rather than a rule of thumb, and every assumption is on the page where you can disagree with it.
- Reservoir
- 200 L
- Circulation
- 600 L/h
- Peak delivery
- 26 L/h
- Daily water
- 48 L
- Chiller
- 161 W ≈ 0.22 HP
- Aeration
- 1.7 L/min
Of that cooling load, 99 W leaks in through the tank wall and 30 W is the circulation pump putting its own power straight into the water — which is not a rounding error and is the figure most often left out. It pulls the tank down one degree in about 86.7 minutes, which is what decides whether it can recover from an afternoon.
The bill of materials
One tent, one reservoir. The desktop app hosts the hub in-process — there is no separate machine. 1 ESP32-S3. Direct I²C and 1-Wire, a few relays.
Installed and reading in under thirty minutes, or the funnel is broken before it starts.
| Item | Qty | Each | Line |
|---|---|---|---|
| ESP32-S3 development board | 1 | ₹900 | ₹900 |
| DS18B20 water temperature probe Two: one in the tank, one at the root zone |
2 | ₹400 | ₹800 |
| Analogue pH probe and interface board | 1 | ₹2,800 | ₹2,800 |
| Analogue EC probe and interface board | 1 | ₹2,600 | ₹2,600 |
| Float switch, reservoir level Low level and overflow |
2 | ₹250 | ₹500 |
| Hall-effect flow meter Not optional on NFT |
1 | ₹350 | ₹350 |
| 4-channel relay board, opto-isolated | 1 | ₹450 | ₹450 |
| Peristaltic dosing pump, 12 V pH-down and one nutrient part |
2 | ₹1,400 | ₹2,800 |
| IP65 enclosure, DIN rail and glands | 1 | ₹1,500 | ₹1,500 |
| 12 V 5 A supply and DC-DC converters | 1 | ₹800 | ₹800 |
| RCD/ELCB for the mains section Mandatory. Standing water and mains voltage share this box |
1 | ₹1,200 | ₹1,200 |
| Cable, ferrules, terminal blocks | 1 | ₹700 | ₹700 |
| Total, ex-GST | ₹15,400 | ||
Mid-2026 street prices for the Indian market. They will be wrong within a year and they are here anyway, because a bill of materials with no numbers in it is one nobody can make a decision from. Anything imported carries customs and freight that are frequently more than the part.
Electrical safety is not a line item. The RCD is in the list because it is mandatory, and the panel work at the Farm and Commercial tiers is engineered rather than assembled. Have the mains section reviewed by a licensed electrical engineer before anything is sold or installed.