High Low Raft System
There is a lot of innovation in Aquaponics, almost too much, as it distracts the new comer from learning the basics. Here is some info on a simple but cleaver approach to High Low raft Aquaponics, for small systems.
Raft way covered with plywood top, drilled with holes each containing net pots holding plants.
Water fills to maximum level of ¾ height of pot and water drains to minimum level of ¼ height of pot
There are several ways to do this but one is to have a pump on a timer with a minimum water level drain pipe that drains slower than the pump adds water, and a maximum water lever drain that drains faster than the pump adds water. This causes a raft way to fill to the maximum level when the pump is on and drain to the minimum level when the pump is off, causing an easily set high low water level.
Air is pulled into plants in net pot when water drains to minimum water level
Less costly way to do rafts, Plywood and paint $15, Expanded Polystyrene (EPS or Styrofoam) and paint $54
Water in Raft way is covered with no place that the sun can get in to grow algae and no place for debris to enter into water.
Raft width limited by practical width of raft, example 2 foot maximum raft width due to weight of plants causing plywood to sag.
Plywood ages quicker than Expanded Polystyrene (EPS).
Plants are not easily movable in raft way. Floating rafts can be easily slid around on the water. This saves on bending and allows wider raft ways while still allowing plants to be easily reached
Less insulation of the water when plywood raft covers used.
High low raft system is useful for small Aquaponic raft based systems and less expensive than using floating Expanded Polystyrene (EPS). It is only practical for small systems where it helps cut down on Algae growth and debris getting into the water.