Lettuce
The crop that kills more Indian NFT builds than any other, and never for the reason the grower thinks. It is almost never the nutrient. It is that the solution reached 28 °C in a black tank on a terrace, dissolved oxygen fell below 5 mg/L, and Pythium took the roots in a week. Chill the water or shade the tank; everything else on this list matters less.
What kills this system: Flow sensor mandatory. Loss of flow raises a critical alarm within 60 seconds.
| Stage | Days | pH | EC mS/cm | Water °C | DO mg/L | Light |
|---|---|---|---|---|---|---|
| Nursery | 12 | 5.6 – 6.2 | 0.70 – 1.10 | 21.0 | 6.5 | 14h |
| Weak feed. A seedling with a small root system in a strong solution does not grow faster, it burns. | ||||||
| Grow-out | 21 | 5.5 – 6.2 | 1.20 – 1.60 | 20.0 | 6.5 | 14h |
| Hold EC down as air temperature rises. The plant takes water faster than salt in the heat, so a fixed EC target quietly becomes a higher one at the root. | ||||||
| Finish | 7 | 5.5 – 6.2 | 1.00 – 1.40 | 19.0 | 6.5 | 14h |
| Dropping EC in the last week reduces nitrate in the leaf, which matters for anyone selling into a retailer that tests for it. | ||||||
Download as a .hydrorecipe file Run it against your water
A plain JSON file with no account attached to it. Pull it onto a controller with curl from a shed, or send it to the farm down the road as an attachment.
Every band on this site is a literature-derived starting point. None of them has been measured on your water, your cultivar or your polyhouse, and the variable that decides most of it — the alkalinity of what comes out of your borewell — is one this page cannot know. Validate on a small block before you commit a season.