Synergy Reef
16″ Shadow® Overflow V3 2500 GPH
16″ Shadow® Overflow V3 2500 GPH
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MSRP $249.99
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What is the Shadow® Overflow?
The Shadow® Overflow is a device that is used to divert water flow from your aquarium into your filtration sump. This overflow can be used on any Freshwater, Marine or Reptilian habitats. There are no limitations on where you can use this overflow system.
What's Included?
What's Included?
Includes the following with the kit:
- Front Overflow Box
- 1 Removable Polycarbonate Locking Front Weir
- 2 Polycarbonate Bulkhead Nuts
- Seamless Rear Box with 3 x 1.5″ Slip fittings
- Locking Polycarbonate Rear Lid Cover
- 2 U-Flow™ 90º Fittings
- 4 Gaskets
- Drilling Template (V1 and V2 are the same hole pattern)
Key Features of the V3 Shadow® Overflow
Key Features of the V3 Shadow® Overflow
- Removable Sealed Rear Lid and Rear Box Design – Rear Lid and Rear Box flange makes a watertight seal. This helps completely reduce salt creep formation on the exterior box. The V3 Rear lid and Rear box is virtually watertight and prevents any water from exiting the box. No other overflow on the market has this capability.
- 1.5″ Exterior Box Slip Fitting Openings – The 3 x 1.5″ Slip fitting openings in the rear box. This gives you maximum flow with a very small external box footprint. The smallest external box to flow rate ratio available. These can easily be reduced to 1" or smaller if needed!
- Re-Engineered Polymer Construction – The Rear Box Material has been changed to a proprietary new polymer blend! This new polymer allows you to use ANY type of PVC or ABS glue or primer you choose. This means that you can use any PVC Cement that you can find locally or have on hand already. It also makes the rear box even more durable than before!
- Quiet Flow™ Weir design – The Shadow V3 now has a redesigned weir that makes it the quietest front weir box available. We have re-engineered the front internal box and designed an integrated Quiet Flow™ system. This allows for the same high surface skimming capability with no noise from internal flow pumps or wave makers.
- Ultra Slim Profile - The ultra slim compact design means that there is no intrusive box inside your aquarium. Even the outside rear box is compact and will not be seen!
- Fail-Safe Operation - With the 3 pipe design, there is no chance for a "overflow" of your aquarium, pun intended! The Safety features built in allow for a worry free system!
- Upgrade-able! – Our Current Shadow V1 or V2 customers can easily upgrade their overflows to the V3. V2 Customers can easily upgrade without any re-plumbing of your system. And The V3 will be upgrade-able with any future advancements.
Unlock Superior Filtration with the Synergy Reef Shadow® Overflow
Unlock Superior Filtration with the Synergy Reef Shadow® Overflow
Our overflow system is the outcome of extensive testing and development, establishing a new benchmark for aquarium filtration. Experience a seamless, plug-and-play solution and learn why the Synergy Reef Shadow® Overflow is favored by aquarium enthusiasts. Eliminate bulky overflow boxes for high flow rates in a compact design.
The Story Behind the Synergy Reef Shadow® Overflow
The Story Behind the Synergy Reef Shadow® Overflow
Our Story - As passionate reef hobbyists, we knew firsthand the frustrations of traditional overflows: bulky designs, loud operation, and limited flow rates. So, we set out to create a game-changing solution. In 2011, we began designing the Ghost Overflow, which would later become the Synergy Reef Shadow Overflow, and over the past decade, we’ve rigorously tested and refined our vision.
A Decade of Innovation and Refining - Our goal was clear: to craft a low-profile, quiet, and high-flow internal overflow box that would meet the demands of discerning reef enthusiasts and aquarium hobbyists. We leveraged cutting-edge 3D software to push the boundaries of innovation, incorporating features that would have been impossible to achieve by hand. Through extensive testing and iteration, we’ve perfected our design.
From Prototype to Perfection - Initially, we handcrafted each overflow using flat acrylic sheets, but this method had its limitations. To make our vision accessible to all, we incorporated the use of injection molding, a process that no other manufacturer has adopted. While others still rely on outdated methods to build their copycat versions, we’ve raised the bar with our cutting-edge design. This allows us to mass-produce our overflow with precision, consistency, and unparalleled quality.
How is it installed? What do I Need?
How is it installed? What do I Need?
This is a self-install kit. You can drill the tank yourself or have a aquarium builder do it for you and install this yourself! Instructions are located here: 16″ Shadow® 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: 16″ Shadow Overflow Drilling Template
A Proven Track Record
A Proven Track Record
A Proven Track Record
With over a decade of testing and refinement, the Synergy Reef Shadow® Overflow has proven itself to be a reliable and high-performance solution. We’re proud to offer a product that has been battle-tested in various aquarium environments.
Evolution to the Shadow® Overflow
As our design evolved, so did its name. We rebranded the Synergy Reef Shadow Overflow® from the Ghost Overflow in 2014, reflecting its sleek, low-profile design that seamlessly integrates into your aquarium.
Q&A
Q&A
Q: What tank thickness will the Shadow® Overflow work
with?
A: The Shadow® Overflow is compatible with tank walls from 0.25"
(6mm) up to 0.945" (24mm), including both glass and acrylic tanks.
Q: What is the maximum flow rate of a 16" Shadow®
Overflow?
A: Each 16" Shadow® Overflow can handle flow rates from as low as
150 GPH up to 2,500 GPH. Whether you're running a small 10-gallon system or a
400-gallon display, the 16" unit is highly efficient. Need more flow?
Simply add a second overflow.
Q: What size aquarium is the 16" Shadow® Overflow
designed for?
A: It’s not about the size of the tank—it’s about the flow rate
you plan to run. One 16" unit supports up to 2,500 GPH, making it suitable
for tanks from 10 to 400 gallons. For larger setups or higher flow needs, use
multiple overflows.
Q: How much space is needed behind the aquarium and wall
for the overflow to fit?
A: A minimum of 4” of space is
needed.
Q: Can the Shadow® Overflow be used in freshwater tanks?
A: Absolutely. Thousands of freshwater aquarists rely on the Shadow®
Overflow. It works in any setup utilizing a sump beneath the tank.
Q: Why don’t you offer larger front weirs like 24"?
A: Our R&D over the past decade shows that longer weirs reduce
efficiency and increase dead zones inside the front box. The 16" size
provides optimal flow dynamics and compact footprint, delivering maximum
performance without compromising space.
Q: What’s the difference between the 16" Shadow®
Overflow and the discontinued 20" Overflow you used to sell?
A: The current 16" Shadow® Overflow is injection-molded, providing
superior durability, precision, and consistency. This advancement allowed us to
fit three 1.5" drains into the compact rear box—something that
wasn’t possible with the original hand-built version.
The now-discontinued 20" model was hand-crafted from
acrylic and created specifically to house three 1.5" drains, which
required a larger footprint at the time. Once injection molding made it
possible to achieve the same functionality in the smaller 16" design, the
20" model became unnecessary and was phased out
Q: Will a longer weir increase surface skimming?
A: No. Surface skimming depends on flow rate—not weir length. Water
volume moving through the overflow determines skimming efficiency. The width of
the weir does not equate to better performance and can actually decrease the
efficiency.
Q: Can I remove the weir (teeth) for cleaning?
A: Yes. The weir is snap-fit and easily removable for cleaning. You can
also purchase an extra weir to swap out during maintenance. The system
continues operating normally even with the weir removed. And once installed,
it’s securely locked into place—no risk of accidental dislodging.
Q: Do I need to upgrade my existing Shadow® Overflow?
A1: If you have a V1 (Serial #0000–5000), We recommend purchasing
the V3 if you are needing replacement parts or just want a new overflow. The V3
is far superior to the older V1 (they were released in 2015!)
A2: If you have a V2 (Serial #5001 and up), no
upgrades are necessary. V2 and V3 are compatible. To convert your V2 to a full
V3, you can purchase the optional internal plate for the front box. Contact us
for upgrade links.
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Installing the Shadow® V3 Overflow Kit
I installed it on my 75 gallon tank. Works great so quiet once tuned in. Synergy provided get information from drilling holes to installing and adjusting. Super quite great product!!!
For large aquaria this is the only overflow that can handle high gph in a single unit.
Very well crafted unit. High quality overflow
Works flawlessly for my 310gal aquariums. Only need one gate valve to fine tune the sound out of the drain. Quality product. Highly recommend.
I've been using the overflow for over a year now and am really enjoying the very low noise the box is outputting altough I am running a lot of flow through it! Surface skimmer is perfect and cleaning is very easy. Great design!