Professional Greenhouse Trays — Pots and Growing Media > Pots and Saucers > Trays

Staal & Plast Polystyrene Glue is a professional adhesive developed specifically for assembling, extending and repairing EBB & Flow trays made from high-impact polystyrene (HIPS). The formula is made from the same material used to manufacture Staal & Plast trays, ensuring an exceptionally strong, waterproof and long-lasting bond between individual elements. It is suitable for both new installations and repairs to professional irrigation systems.

Staal & Plast polystyrene glue is specially developed for the manufacturer's professional EBB & Flow systems and guarantees reliable, durable bonding of individual trays. Unlike universal adhesives, it contains high-impact polystyrene (HIPS), identical to the material used to manufacture the trays themselves. This allows the materials to bond virtually as one, providing a strong, watertight joint.

When building large EBB & Flow tables, the manufacturer recommends initially fixing the trays with hot-melt glue for correct positioning and to maintain the required installation joint. The polystyrene glue is then used to permanently bond the individual trays together, providing a strong connection.

The adhesive is suitable for both new installations and repairing damaged trays. Once fully cured, it forms a strong, durable bond that withstands constant contact with water, nutrient solutions and the usual conditions in greenhouses and professional production facilities.

The manufacturer recommends applying the adhesive evenly and sparingly. Excessive amounts can damage the trays, and such damage is not covered by the warranty.

Technical specifications

✔️ Manufacturer: Staal & Plast A/S

✔️ Type: Polystyrene adhesive (HIPS)

✔️ Purpose: Assembly and repair of EBB & Flow trays

✔️ Material: High-quality polystyrene (HIPS)

✔️ Provides a waterproof, permanent bond

✔️ Suitable for professional irrigation systems

✔️ Full curing time: 48–72 hours at approximately 20°C

✔️ Lower temperatures increase drying time

✔️ Once cured, the bond is permanent and cannot be disassembled without damaging the material.

📦 Available sizes

✔️ 300 ml cartridge

✔️ 2.5 litres

✔️ 5 litres

✔️ 10 litres

✔️ 20 litres

📏 Material consumption

✔️ 300 ml – approximately 6 linear metres of adhesive bead

✔️ 1 litre – approximately 20 linear metres of adhesive bead

Application

Suitable for:

• Installation of EBB & Flow trays

• Expansion of professional irrigation tables

• Repair of HIPS trays

• Manufacture of greenhouse tables

• Vertical farms

• Nurseries

• Professional greenhouses

• Hydroponic systems

📋 Instructions for use

1. Position the trays and leave the recommended installation joint.
2. Temporarily secure them with hot-melt adhesive if necessary.
3. Apply an even layer of polystyrene adhesive along the entire length of the joint.
4. Allow the adhesive to cure for 48–72 hours at a temperature of around 20°C.
5. Do not use or fill the system with water until the adhesive has fully cured.

⚠️ Important: Do not apply excessive amounts of adhesive. Excess adhesive can damage the trays, and such damage is not covered by the manufacturer's warranty.

💡 Urban Botaniks tip: When building large EBB & Flow tables, use the original Staal & Plast adhesive. Thanks to the same HIPS material used for the trays, it creates an exceptionally strong, durable bond that withstands daily use and constant contact with water and nutrient solutions.

Standard greenhouse trays – efficient irrigation and optimal use of space

Trays with a closed bottom are ideal for:

• "Ebb and flow" irrigation systems (Ebb & Flow)
• They offer exceptional flexibility in plant placement
• Close placement at the initial growth stage and wider spacing in subsequent phases.

Available only on request and with the possibility of custom dimensions and type to meet your specific needs.

Available types:

Type 1: Best-selling model

Equipped with large longitudinal and small transverse channels, this design ensures even water distribution, a sturdy construction and exceptional stability. The tray is available with the standard one or two valves at the end, and their position can be customised to the customer's needs.

Type 2: Special model for small pots

This model has only longitudinal channels for easier cleaning and optimal water distribution. Suitable for small pots, it offers the same possibility of valve customisation to meet the specific requirements of your system.

Type 3: Model with improved transverse strength

Designed for automated systems with frameless benches, this model has improved transverse strength and stability. It allows transport trolleys to move easily along the benches without the need for additional aluminium protection.

Custom dimensions and requests
The trays are available in a variety of standard sizes, and special dimensions and configurations can also be made on request to meet the requirements of your greenhouse.

Advantages

• Efficient irrigation in every growth stage
• Flexibility in placement of plants
• Sturdy and durable construction
• Customisation options for dimensions and configurations

The ideal solution for every greenhouse seeking optimisation and sustainability when growing its produce!

The conical rubber plug has a diameter of 26/32 mm and works as a stopper (like a cork). It is mainly used in commercial vessel systems (such as Ebb & Flow trays) to prevent leakage until the tray is flushed through the drain hole.

Detailed features

• Type: conical rubber plug, working like cork stoppers.
• Size: 26/32 mm (in the context of Ø 28–32 mm) — corresponds to the stated range.
• Application: Closes trays during flooding; after installation, when the plug is removed, it allows filling with fresh water and flushing soil and residues through the drain hole.

Recommendations for use

• When installed, the plug seals the tray completely, allowing flooding without leakage.
• After removing the plug, the system automatically allows waste to drain. This makes cleaning and preparing the tray again easier.

Benefits

The rubber plug is a practical and inexpensive solution for controlled filling and draining of trays. It is easy to fit and provides a reliable seal during filling; removing it allows efficient rinsing and cleaning without additional mechanisms. This gives maximum control over the irrigation cycle.

HS Valve is a single-channel valve that uses the same channel for both filling and tray drainage. It is supplied as standard with a 3.5 mm internal opening, but the diameter can be modified on request. The valve offers 6 – 31 l/min filling, depending on the diameter and pressure, and 1.7 – 6 l/min drainage. Suitable for installation below filters, it is resistant to contamination and aggressive environments.

Detailed features

• Operating function: single-channel – one line serves both filling and drainage.
• Opening diameter: standard 3.5 mm, other sizes on request.
• Filling flow rate: from 2.3 to 31 l/min, depending on the opening diameter and water pressure.
• Drainage flow rate: from 1.7 to 6.0 l/min, depending on the opening diameter.
• Hose-connection options:
  • ¾″ hose
  • ½″ hose
  • PE hose 8×10.5 mm and 10×12.5 mm
  • PE hose 6×8 mm ([turn0view0])
• Manual bottom valve: allows filling to a specific tray to be stopped.
• Installation option: installed below the filters to prevent clogging from leaves and contaminants.
• Construction and maintenance: durable design, resistant to demanding growing conditions, with a removable internal cone for easy cleaning.

Recommendations for use

• Choose a suitable orifice diameter (3,5 mm or another size on request), matched to the water pressure for the desired filling and drainage flow rate.
• Install the valve beneath the tray filter to ensure protection from contaminants and trouble-free operation.
• Use the manual bottom valve when you want to stop filling a particular tray.
• Cleaning is easy — simply disassemble the removable cone and remove the accumulated particles.

Benefits

• Unified filling and drainage line — fewer components and easier installation.
• Wide flow range — from 2,3 to 31 l/min for filling and from 1,7 to 6,0 l/min for drainage, depending on the conditions.
• Flexible connection options for various hoses (½", ¾", PE).
• Easy installation below filters and excellent resistance to contamination.
• Robust construction and easy servicing ensure a long service life.

Quick Valve is the fastest and most commonly used valve for EBB & Flow trays. It is dual-channel: one channel fills the tray and the other drains it. When the water supply stops, the valve automatically drains at ~28 l/min. It comes standard with an internal opening of 4 mm (other diameters available on request). Installation beneath filters is recommended to protect against leaves, soil and debris.

Detailed features

• Function: dual-channel (fill + drain); the drainage channel oxygenates the irrigation water during filling for better root development.
• Filling flow rate: ~9–40 l/min depending on pressure and the internal diameter of the opening; standard 4 mm, other diameters on request.
• Automatic drainage: ~28 l/min when water supply stops.
• Manual bottom valve: yes — lets you avoid filling a specific table/tray.
• Connections (options):
  • ¾″ hose
  • ½″ hose
  • PE 8×10.5 mm and 10×12.5 mm
  • PE 6×8 mm
• Installation: countertop hole Ø 27 mm for recessed fitting; can be installed beneath sump plastic filters.
• Durability: designed for years of use in a demanding production environment.

Recommendations for use

• Select the internal opening (mm) according to the available pressure to achieve the desired filling flow rate.
• Install the valve under a filter (sump) to prevent blockage by debris.
• When you need to shut off a particular table, use the manual bottom valve.

Summary – Benefits

• Fast filling with an adjustable flow rate based on opening size and pressure.
• Automatic drainage of ~28 l/min when water supply stops.
• Improves irrigation water quality through oxygenation during filling.
• Flexible options for ½″, ¾″ and PE connections.
• Durable construction for a long service life in greenhouse conditions.

Cover for Sump is a cover designed to seal an existing sump in a tray when you wish to disconnect it from the system. Covering it prevents contaminants from entering and makes it easy to deactivate the sump in the tray without removing it. 

Detailed features

• Product type: sump cover — used when you wish to "remove" or deactivate the sump in a tray.
• Installation instructions:
  1. Clean and dry the area around the sump.
  2. Apply Staal & Plast adhesive along the edge of the cover and allow it to bond.
  3. Seal the edges to ensure a tight, waterproof finish.
• Note: For optimal results, follow the instructions in the dedicated technical glue product sheet ("glue product sheet").

Recommendations for use

• Ensure the surface is properly prepared — clean and dry — before bonding.
• Use the original Staal & Plast adhesive product to ensure stability and durability.
• Seal the edges of the cover after installation to prevent dirt and moisture from entering.

Benefits

The sump cover allows easy and secure deactivation of the sump in a tray without dismantling it. It makes system management easier when a temporary or long-term change is needed, while preventing contamination through strong bonding and quality sealing.

Siphon Valve is a simple yet effective drainage valve with a siphon. It allows a tray to drain automatically to a selected level by adjusting the lift tube (“riser”). Suitable for automated mobile systems, it can provide continuous drainage if the riser is fully removed.

Detailed features

• Level adjustment: Three preset water retention and drainage levels, set by moving the riser tube.
• Continuous drainage: If the riser is fully removed, the valve drains the tray completely.
• Full tray: With the riser in its highest position, water is retained in the tray.
• Drainage: Depending on the hole diameter — standard without a reduction ring: 17.5 mm internal diameter provides a maximum drainage rate of 9 l/min. Other sizes are available on request.
• Rubber gasket: Includes a standard 10 mm rubber gasket, compatible with standard sump filters. An optional 5 mm gasket is also available. The gasket height affects the operating water level in combination with the riser settings.
• Installation: It is possible to use 1 to 3 Siphon Valves in already constructed sump filters. The filters allow easy removal of the lid and installation of the valve.
• Construction: Very robust and resistant to demanding growing conditions. Easy to disassemble for regular cleaning.

Recommendations for use

• Adjust the riser pipe to the desired filling and drainage threshold (3 levels or continuous drainage).
• Use the standard 10 mm rubber gasket for optimum performance with standard sump filters. If you require a different retention level, look for the version with a 5 mm gasket.
• Install 1–3 valves according to your needs and the available space in the filters — they are easy to fit and remove.
• Regular cleaning is simplified thanks to the robust, detachable design.

Benefits

The Siphon Valve provides reliable, automatic draining of trays to a preset level through a siphon effect. The standard 10 mm rubber gasket ensures easy integration with sump filters, while the design is durable and easy to maintain. The option to use up to three valves in one system provides flexibility and control.

Repair Piece for Sump is a solution for repairing damaged sump tray wells. It is made in dimensions of 175 × 55 mm and allows easy replacement of defective sections—without the need to replace the entire tray.

Detailed features

• Dimensions: 175 × 55 mm — suitable for restoring damaged areas in sump trays.
• Installation: Clean and dry the surface of the damaged section. Apply the branded Staal & Plast adhesive, position the Repair Piece and, if necessary, seal the edges to ensure a strong and waterproof bond.
• Additional work: After fixing, it may be necessary to drill new holes for valves if the original ones fall within the new area.

Recommendations for use

• Prepare the surfaces thoroughly—they must be clean and dry before bonding.
• Use the original Staal & Plast adhesive to ensure durable and resilient bonding.
• After installation, if necessary, seal the edges with sealant to prevent the ingress of dirt and moisture.
• If sump valves need to be installed, you can drill new holes in the repaired section.

Benefits

The repair piece for sump trays provides an economical and reliable repair for damaged sections, without the need to replace the entire tray. Its 175×55 mm size allows precise replacement. Natural bonding and sealing guarantee tightness and long-term functionality, including the option of fitting new valves.