Monday, 23 March 2020 20:55

Flood Table and Tray Setup

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A flood table and tray system is a very simple and mostly handsoff way of growing foods like microgreens, leafy greens, small herbs. This is a great method for larger setups that require turning over seedlings and microgreens.


A flood table as the name suggests is a kind of table surface system that floods water in a variety of ways. Growing vessels can be held on the table and watering is pumped in from a reservoir which can be timed. The size of the flood table will dictate any number of ways to grow plants. You can have shallow tables that contain seedling or mini/micro-green trays, or deeper ones that can contain a hydroton medium for growing deeper root plants such as vegetables.

The table is placed on an even surface with holes drilled into the table and shelf allowing for two bulkhead fittings to be installed as shown in the pictures below. Half inch tubing is used to both supply and drain the table into a reservoir.


  • High density, set and forget watering system
  • You can choose a neutral medium with hydroponic nutrients, or you can use extra vermiculite with soil for organic growing
  • A flood table is watered from below which can help combat humidity leading to pests and disease
  • Very low failure, unlikely to leak or flood even if your pump goes bonkers


  • Your medium needs to be tuned carefully to the water cycle
  • You cannot mix different mediums and water cycles unless you have a 
  • The trays need cleaning on a moderate basis. Salt buildup occurs from the nutrient

The water resides in a tank on the floor with a pump. That pump can be controlled by any simple timer. There are two methods for providing the water to the trays on a schedule

Ebb & Flow

A water resevoir below has a pump which is activated on a timer. Water pumps and floods the tray through the supply. A drain sits next to the supply, and while it seems counter-intuitive, the water flows into the table long enough to wick into the tray medium. Then when the timer goes off, a minute or so later the water fully drains back out, not getting stagnant.

The drain can be adjusted to a certain depth. The timing of the pump depends on how much water needs to be pumped to achieve a certain level. The growing reservoir can be as deep as you like, with medium such as hydroton if you desire deeps vessels capable of growing things like fruiting trees. When the pump finishes its cycle and turns off, the supply vent which is flush with the growing tray now becomes a drain as well, thus ensuring you can go from completely full to empty within a period of time.

Bell Syphon

In this system the pump runs constantly and the bell syphon is a simple yet elegant composition of pipes within each other. A drain pipe is protected by a standpipe which forms a waterproof seal. When the water level rises to the top of the standpipe, it floats and allows all of the water to drain. The bell syphon driain usually is much larger than the supply so water drains quicker than it is supplied as the pumps always run.

The Bell Syphon system is more ideal for large growing vessels and are generally not stackable. You also need a much larger water mass which makes it ideal for aquaponics.


These materials are readily available and can be built from scratch. 



Read 1233 times Last modified on Tuesday, 07 April 2020 11:09

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