Page "Hydroponics" Paragraph 30

As a general guide, flow rates for each gully should be 1 liter per minute.

At planting, rates may be half this and the upper limit of 2 L / min appears about the maximum.

Flow rates beyond these extremes are often associated with nutritional problems.

Depressed growth rates of many crops have been observed when channels exceed 12 metres in length.

On rapidly growing crops, tests have indicated that, while oxygen levels remain adequate, nitrogen may be depleted over the length of the gully.

As a consequence, channel length should not exceed 10 – 15 metres.

In situations where this is not possible, the reductions in growth can be eliminated by placing another nutrient feed halfway along the gully and reducing flow rates to 1 L / min through each outlet.