A hang-on-back sump setup can add filtration or refugium capacity without placing equipment inside the aquarium, but products in this category do different jobs. The Fiji Cube is a dedicated hang-on-back refugium, while the SIHDYRDBY filter is an all-in-one filter with a waste sump chamber. The nano marine filter suits compact saltwater tanks, the Coral Vue Octopus is a hang-on-back protein skimmer, and the Fabater is an overflow box for routing water to a separate sump.
| Product | Best For | Type |
|---|---|---|
| Fiji Cube Hang On Back Refugium Pro (Large) | Adding a separate refugium | Hang-on-back refugium |
| SIHDYRDBY Filter With Waste Sump Chamber | Visible waste collection and layered filtration | Hang-on-back filter |
| Nano Marine Hang-On Filter Box | Compact saltwater setups | Modular filter box |
| Coral Vue Octopus AC20538 | Hang-on-back protein skimming | Protein skimmer |
| Fabater Overflow Box | Sending aquarium water to a separate sump | Overflow box |
Fiji Cube Hang On Back Refugium Pro
This product is the most direct match for an aquarist searching for a hang-on-back refugium. Its name identifies it as a large refugium that hangs on the aquarium rather than sitting inside the display. A refugium is a separate area used as part of an aquarium system; it is not the same thing as a conventional mechanical filter or an overflow box.
Best for: Aquarists who want a dedicated hang-on-back refugium and prefer to keep auxiliary equipment outside the main display. It was selected because it is explicitly identified as a refugium. The provided listing information does not include dimensions, included accessories, or filtration details, so check those specifications before choosing it.
Consider: “Large” does not provide a precise fit measurement. Confirm available tank clearance and the unit’s dimensions before purchase.
SIHDYRDBY Filter With Waste Sump Chamber
This hang-on-back filter combines surface skimming, a clear waste tray, and dual-stage filtration. The tray collects fish waste and larger debris, while a dedicated drain outlet is intended to make waste removal easier. The product also describes adjustable water flow, two inlet-pipe installation styles, and removable filter baskets.
Best for: Fishkeepers who want visible debris collection and multiple filtration functions in one unit. It is a better fit than a basic refugium when the priority is routine filtration and waste handling, rather than a dedicated refugium chamber.
The manufacturer recommends rinsing sponges every 7–10 days and cleaning filter media in batches every 1–2 months. Consider: This is a filter with a waste sump chamber, not necessarily a complete, separately installed aquarium sump.
Modular Nano Marine Hang-On Filter Box
This wall-mounted filter box is described for small saltwater setups and is listed as fitting 40-liter bare tanks with direct hanging installation. Its modular structure has independent filtration compartments and supports upgrades with a protein skimmer or automatic filter-paper dispenser. The listing describes multi-stage filtration intended to remove impurities and help stabilize water quality.
Best for: Nano marine aquarium owners seeking a compact, customizable filtration box that hangs outside the tank. The stated setup size and upgrade options make it a more targeted choice for small saltwater systems than a general-purpose filter.
Consider: The stated fit is specific to 40-liter bare tanks; verify tank configuration and mounting fit. The product description does not establish that skimmer or paper-dispensing accessories are included.
Coral Vue Octopus AC20538 With 1000 Pump
The listing identifies this as a four-inch Coral Vue Octopus hang-on-back unit with a 1000 pump and a stated 100-gallon designation. It is a specialized option for aquarists looking for a hang-on-back protein skimmer, rather than a complete sump with multiple filtration chambers. Coral Vue is described as a subsidiary of Vue Technology and a U.S. distributor of Reef Octopus products.
Best for: Aquarium keepers who specifically want a hang-on-back skimmer and are comparing equipment by the listed pump and capacity designation. It was selected because it provides a distinct skimming option for systems where that function is the priority.
Consider: The provided details do not explain included plumbing, installation requirements, or the meaning of the 100-gallon designation for different aquarium setups. Confirm the product specifications for your system.
Fabater Self-Starting Overflow Box
The Fabater is an acrylic hang-on overflow box, not a sump by itself. Its listed 5000LH specification and self-starting mechanism are intended to help move water from an aquarium toward a separate sump system. The description says it includes a check valve and syringe for priming. A movable outlet cover is intended to reduce water noise, and an overflow comb helps block fish, plants, and particles from entering the chamber.
Best for: Aquarists assembling a separate sump system who need an overflow component. The priming features and debris protection distinguish it from the all-in-one hang-on filters above.
Consider: An overflow box requires a separate sump and appropriate system setup; it does not provide filtration on its own.
Buying Guide: How To Choose A Hang-On-Back Sump
Do you need a refugium, filter, skimmer, or overflow?
Start by identifying the job. Choose a refugium when you want a dedicated auxiliary chamber. Choose a hang-on-back filter for its stated mechanical or multi-stage filtration features. A protein skimmer is a specialized option, while an overflow box routes water to a separate sump. These products are not interchangeable, even though they all hang on or connect to the back of an aquarium.
Will the unit fit your aquarium?
Check the product’s dimensions, tank-wall clearance, and stated setup requirements. The nano filter listing specifically names 40-liter bare tanks, while the Fiji Cube listing calls its model large without providing dimensions in the supplied details. Do not assume that a product fits every aquarium based on its hang-on-back design alone.
What maintenance will it involve?
Compare how the product handles waste and access to filter media. The SIHDYRDBY filter lists a visible waste tray, drain outlet, and removable baskets, alongside cleaning intervals for sponges and media. The nano marine box emphasizes independent compartments and modular disassembly. Review the care requirements and plan for routine cleaning rather than relying on filtration equipment to eliminate maintenance.
Are you building a complete sump system?
If you want a separate sump, an overflow box is only one component. Confirm the rest of the system’s requirements before buying. If you want equipment that hangs directly on the display aquarium without a separate sump, compare the refugium, filter box, and skimmer options instead.
Frequently Asked Questions
Is a hang-on-back filter the same as a hang-on-back sump?
No. A hang-on-back filter is a filtration unit, while a sump is a separate reservoir or chamber in an aquarium system. Some products use “sump chamber” to describe a collection area inside a filter, so check the product’s actual function.
Does the Fabater overflow box include a sump?
The listed product is an overflow box. Its description does not say that a separate sump is included.
Which option is specifically a refugium?
The Fiji Cube Hang On Back Refugium Pro (Large) is the product explicitly identified as a hang-on-back refugium in the supplied listing.
Which product is described for a 40-liter tank?
The modular nano marine hang-on filter box is described as fitting 40-liter bare tanks with direct hanging installation.
Can one product perform every filtration job?
Not based on the supplied product details. The options have distinct stated roles, including refugium, multi-stage filter, protein skimmer, and overflow box. Choose according to the function your aquarium system needs.