Measure the reservoir length, width and height in centimetres and the working fill depth, leaving 15–25% headroom so root and media mass never overflow.

Compute the gross litres — L × W × H ÷ 1000 — and the usable litres scaled by the working depth fraction.

Pick the system turnover duty (DWC 1×, NFT and Dutch bucket 2×, ebb-and-flow 4×) and size the pump with the head and leak multipliers applied.

Check the delivery against the rated pump curve — head derates output toward the max-head ceiling — and confirm the line velocity stays in the 0.5–1.5 m/s band.

Dose the sanitation: ≥2 ppm active HOCl from a 500 ppm stock, 50–100 ppm peroxide, or a UV-C lamp sized at ~1 W per 40–50 GPH, and hold the temperature-adjusted contact time.

Grade the root-rot risk from temperature and the active sanitation line: green ≤22°C sanitized, yellow 22–24°C, red >24°C unsanitized.