20″ Synergy Reef Overflow (For tanks over 3/4″ thick)


For thicker aquariums up to 1.5″ thickness. This is  SPECIAL ORDER ONLY.

This item is BUILT TO ORDER and SHIPS 1-2 Weeks after ordered


SKU: 20overflow Category:


The 20″ Synergy Reef Overflow™ is our only overflow that will work with tanks over 3/4″ up to 1.5″ in thickness.  If you need a Synergy Reef overflow for any tank 3/4″ and under please use the 16″ Shadow Overflow. The 16″ and 20″ have the same Flow Rates (2500 GPH) We only make the 20″ for aquariums thicker than 3/4″. This overflow features a magnetically removable weir. Our design has revolutionized the aquarium overflow and aquariums since it was first released.  It is a very simple to install, plug and play overflow system. Completely quiet operation. Don’t be fooled by imitation overflow systems, we are the pioneers that brought this overflow system to the industry first. Our testing and development are where others lack.

This item is BUILT TO ORDER and SHIPS 1-2 Week after order. 



2500 Gallon Per Hour Flow Rates!

Front Overflow Box
20″ x 1.35″ x 5.75″
2 x 1.5″ ABS Bulkheads (Fits up to 1.5″ or 38mm Glass or Acrylic tanks) *** Minimum tank thickness is 3/4″ or 19mm ***
Removable Magnetic Weir (Only overflow design available with this feature, Allows you to clean the teeth on the weir with very easy removal)
1.5″ Water level

Rear Box
20″ x 4.375″ x 7″
3 x 1.5″ ABS Bulkheads for easy removal and replacement
3 Pipe Full Siphon Overflow capability!
Removable Black Polycarbonate lid (reduces noise, eliminates salt creep and light from entering the rear box)


Includes the following with the kit:
Front Overflow Box with 2 x 1.5″ ABS Bulkheads and 1 Removable Weir (extras can be purchased separately)
Rear Box with 3 x 1.5″ ABS Bulkheads
Black Polycarbonate Rear Lid Cover
All Needed rubber gaskets
Drilling Template

This will be a self install kit. You can drill the tank and install this yourself! Instructions are located here: Synergy Reef Overflow™ Installation Manual

Drilling template is included with the overflow and we recommend you use the template when the overflow arrives to align it perfectly. But if you need the drilling template .pdf it is located here: 20″ Synergy Reef Overflow™ Drilling Template .pdf

Here are some of the key features of this overflow:

  • Ultra slim design with the internal overflow only 1.35″ in thickness!
  • Fabricated with interlocking components.
  • Nearly Invisible when installed.
  • Removable magnetic weir with Laser cut teeth for easy maintenance and cleaning. We use corrosion resistant magnets that allow for a smooth action when removing the weir in tight spots under trim on your tank.
  • Dead Silent!
  • Rear box allows for various plumbing combinations, including the popular full siphon system (aka bean animal)
  • ONLY Works on any non tempered and acrylic tanks from 3/4″ (19 mm) up to 1.5″ (38mm) Thick (Rimless and Plastic trimmed tanks all work!)
  • Simple installation, installs in minutes.
  • Designing the overflow –

    Being reef hobbyist’s ourselves, we spent years working on the design of this overflow. We tested hundreds of variations and options before we came to this design. Our fundamental goal was to create the smallest and quietest internal overflow box possible, while maintaining the flow rates desired by the reef hobbyist. We wanted an overflow system that everyone would want to use. Not only did we do the design this overflow in-house, but we have done extensive testing over the past 4 years as well!

  • Manufacturing the overflow –

    We manufacture and assemble this overflow ourselves! 100% built and supported by Synergy Reef Systems in the USA! We control the availability of our own product and are not dependent on someone else. Only the highest quality acrylic is used in our overflow. We do not use lesser quality PVC or other plastics.

    • We use our state of the art precision Spindle CNC to machine all of the interlocking pieces. This allows us to create a high quality durable piece of equipment.
    • Precision laser cut the teeth in the removable weir for a smooth polished finish found nowhere else. This inhibits algae growth inside the teeth. Our overflow does not use routered teeth on the weir.
    • The smooth routered edges of our internal overflow box not only look clean, but will stay clean. We do not leave any overhanging material that will build up with coraline algae and other marine organisms. The smooth surface of the internal box allows for simple scraping and cleaning.
    • Bulkheads are installed inside the front box to provide a smooth surface for the incoming water to flow over. Reduces turbulence inside the overflow. These bulkheads are the highest quality, Made in the USA, that will not deteriorate or need replacement.

Additional information

Weight11 lbs
Dimensions24 × 13 × 12 in


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