To automate the volume and timing of feeds
use a pump and timer to automatically switch the pump on and off (Fig
6.8).
Make sure the pump is capable of delivering
sufficient flow. The final output will depend on the diameter and length
of feed lines, the use of junctions (e.g. elbows, tees), restricted feed
outlets (e.g. drippers) and the height the nutrient will be pumped to
(i.e. ‘head’) - see Fig 6.9b.
When buying a water pump consider also the
following features:
+
Inlet filter: Helps prevent pump failure and
blockage of feed lines, drippers (etc), as a result of debris in the
nutrient.
+
Silent running.
+
Low intake allowing for operation at low
water levels.
+
High resistance to damage resulting from
overheating if the pump runs dry (or preferably one with an auto shut-off
function).
+
Removable filters and impellers to enable
cleaning (Fig 6.9c).
‘Submersible’ pumps offer the following benefits:
+
Avoids 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 solution.
