These can be used as replacement trays in existing benches, or to convert other existing benches into modern Ebb and Flow sub-irrigation benches. The polystyrene bench trays are molded with a network of drainage channels that serve several purposes. First, as the bench tray is flooding, they allow the water to flow evenly throughout the entire surface of the bench tray and rise simultaneously over the entire bench surface, watering all plants on the bench evenly.
- The bench framework must be able to support the ebb and flow trays either completely or with sturdy cross bars spaced no more than 50 cm (19-1/2") apart on the center.
- The existing bench framework must be sturdy and stable, able to support the benchtop, the plants, as well as the water when irrigating (about an additional 4 pounds per square foot).
- The bench must be able to be leveled. Ebb and flow trays must be completely level to function correctly. Ideally, there is a method to adjust the benchtop level at frequent locations (typically at each leg).