automate the volume and timing of feeds use a pump and timer to
automatically switch the pump on and off.
Make sure the pump is capable of delivering a
sufficient flow rate. Apart from the pump’s output capacity,
the flow rate will depend on the diameter and length of feed lines; the
use of junctions; restrictive feed outlets (e.g. drippers); and the height
to which nutrient will be pumped (i.e. ‘head’) - see Fig 2.8b.
When buying a water pump
also consider the following features:
- Removable filters and impellers: This
assists with cleaning and maintenance (Fig 2.8c). Filters help prevent
pump failure and the blockage of feed lines and feed outlets as a result
of debris in the nutrient.
- Low intake allowing for operation at
low water levels.
High resistance to damage resulting from overheating if the pump runs dry
(usually not available for centrifugal pumps). An auto shut-off function
‘Submersible’ pumps offer
the following benefits:
- They avoid priming problems.
- Fewer leakage problems because the
plumbing junctions are within the reservoir.
- Quieter because they are silenced by
the nutrient solution.
- Water cooled by the nutrient