External Hang On Plastic Aquarium Fish Breeding Box Satellite feat

If you’ve been considering entering the world of fish or shrimp breeding, or even raising invertebrates like amphipods and copepods for aquarium food, then you likely have been reading about refugiums. Refugiums allow for tank water to flow through while protecting sick or weak fish, as well as fish that are at risk of predation in the tank, like fry and shrimplets.

Refugiums are a great option for quarantine and breeding, and some can even be used as part of a sump setup. It can be overwhelming and confusing to learn about refugiums, though, so we’ve put together reviews of the six best hang on back refugiums for your aquarium.

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A Quick Comparison of Our Favorites

Image Product Details
Best Overall
Winner
Finnex External Refugium Hang-On Box Finnex External Refugium Hang-On Box
  • Includes adjustable water pump
  • Includes medium to high requirement LED light
  • Includes leveling knobs
  • Best Value
    Second place
    Fluval Hang-On Breeding Box Fluval Hang-On Breeding Box
  • Holds up to ½ gallon of water
  • Sturdy, transparent plastic
  • Includes leveling feet
  • Premium Choice
    Third place
    CPR AquaFuge2 Hang-On Refugium CPR AquaFuge2 Hang-On Refugium
  • Available in three sizes up to 4.7 gallons
  • Black backing
  • Includes a powerhead
  • Sudo Starpet Hang-on Breeding Box Sudo Starpet Hang-on Breeding Box
  • Holds up to ½ gallon of water
  • Includes separators
  • Sturdy, transparent plastic
  • ISTA IF-648 Hang-On Breeder Box ISTA IF-648 Hang-On Breeder Box
  • Includes a lid
  • Includes leveling feet
  • Holds ½ gallon of water
  • The 6 Best Hang on Back (HOB) Refugiums – Reviews 2021

    1. Finnex External Refugium Hang-On Box – Best OverallFinnex External Refugium Breeder Hang-On Box

    The Finnex External Refugium Hang-on Box is not just a HOB refugium, making it the best overall HOB refugium pick. It also includes an adjustable water pump and LED light suitable for medium to high light needs. This kit can also be purchased with a light suitable for low lighting needs and without a light.

    This HOB refugium measures 10.25 inches by 5.5 inches by 5 inches and is made from sturdy plastic. It includes two leveling knobs that help prevent spills, although overflow is possible if the outlet becomes clogged. This refugium also includes removable baffles to help further reduce the water flow if needed for shrimp, fry, or low-flow fish like bettas. The included water pump can run up to 40 gph.

    Pros
    • Made from sturdy plastic
    • Includes adjustable water pump
    • Includes medium to high requirement LED light
    • Can be purchased with low-light LED and no light
    • Includes leveling knobs
    • Features removable baffles
    • Water pump can run up to 40 gph
    Cons
    • Can overflow if outlet becomes clogged
    • Lowest flow may be too strong if baffles are not used

    2. Marina Hang-On Breeding Box – Best ValueFluval Muli-Chamber Holding and Breeding Box

    The best HOB refugium for the money is the Marina Hang-on Breeding Box. It holds up to ½ gallon of water and includes separators to create up to three chambers. The separators feature slats that are just large enough for fry to pass through to become separated from the mother.

    This HOB refugium measures 10.7 inches by 5.8 inches by 5.7 inches and is made from sturdy, transparent plastic. It can be used on rimless aquariums with a minimum glass thickness of 5mm. This HOB refugium includes leveling feet and is available in two smaller sizes as well. It requires the use of an air pump that is not included.

    Pros
    • Holds up to ½ gallon of water
    • Includes separators to create up to three chambers
    • Separators feature slats large enough for fry to pass through
    • Sturdy, transparent plastic
    • Can be used on rimless aquariums
    • Includes leveling feet
    • Available in three sizes
    Cons
    • Air pump is required but not included
    • Can overflow if outlet becomes clogged
    • Requires 5mm thick glass for use on rimless aquariums

    3. CPR AquaFuge2 Hang-On Refugium – Premium ChoiceCPR AquaFuge2 Hang-On Refugium

    For a premium product pick, take a look at the CPR AquaFuge2 Hang-on Refugium. This product comes in three sizes of sturdy acrylic. They include a black acrylic backing that does not allow for light to pass through to the main tank, making this product a great option as a refugium for plants.

    The largest size option of this HOB refugium measures 25.5 inches by 4.5 inches by 12 inches and holds 4.7 gallons of water. This kit includes a powerhead with all three sizes. This product is made with baffles that allow for plants, animals, and substrate in the refugium to remain undisturbed while the water is not allowed to stagnate.

    This product does not include a light but does include space above the water line to place one. The baffles in this kit are not removable and it does not have a lid.

    Pros
    • Made from sturdy acrylic
    • Available in three sizes up to 4.7 gallons
    • Black backing to prevent light bleed into main tank
    • Includes a powerhead
    • Unique baffles system does not allow for stagnation
    Cons
    • Premium price
    • Baffles are not removable
    • Does not include a light
    • No lid

    4. Sudo Starpet Hang-on Breeding BoxExternal Hang On Plastic Aquarium Fish Breeding Box Satellite

    The Sudo Starpet Hang-on Breeding Box is a large, sturdy HOB refugium option. It is nearly identical to the Marina HOB Breeding Box, but at a higher price.

    This HOB refugium does not include an air pump or light, although an air pump is required for its use and a light is recommended. This HOB refugium measures 10.7 inches by 5.8 inches by 5.7, is made from sturdy, transparent plastic, and has two leveling knobs. It also includes two separators with slats large enough for fry to pass through but too large for adult fish to pass through. The slats can be used to turn the box into three separate chambers.

    Pros
    • Holds up to ½ gallon of water
    • Includes separators to create up to three chambers
    • Separators feature slats large enough for fry to pass through
    • Sturdy, transparent plastic
    • Includes leveling feet
    Cons
    • Air pump is required but not included
    • Can overflow if outlet becomes clogged
    • Higher price than other similar products

    5. ISTA IF-648 Hang-On Breeder BoxISTA IF-648 Hang-On Separation Breeder Box

    The ISTA IF-648 Hang-on Breeder Box is made from transparent plastic that may become scratched with rough handling. It can fit over an aquarium edge or rim up to 1 inch in width.

    This HOB refugium measures 10 inches by 5.5 inches by 5.25 inches and holds approximately ½ gallon of water. It has two separators with slats that allow for fry to separate from other fish. You can make up to three chambers with this box. The separators and holders in this product allow for some customization. The box does not include the needed air pump or a light, but it does have a lid. The pump inlet can be loud and may require some adjustments to reduce noise.

    Pros
    • Holds ½ gallon of water
    • Removable separators with slats allow fry to pass through
    • Separators can be placed in different locations allowing for customization of three chambers
    • Includes a lid
    • Includes leveling feet
    Cons
    • May scratch with rough handling
    • Can only fit over 1” rim
    • Air pump is required but not included
    • Pump inlet may be loud and require adjustments

    6. Blue Ocean REF 15 Hang on RefugiumBlue Ocean REF 15 Hang On Refugium Aquarium Filter

    The Blue Ocean REF 15 Hang on Refugium is a premium-priced HOB refugium made from acrylic. It features a black acrylic back to decrease light leaking into the main tank. It is prone to scratching and pieces may break with rough handling. It is also prone to leaking, so you’ll need to watch for this closely.

    This product measures 13.25 inches by 4.75 inches by 12 inches and holds a little more than ½ gallon of water. It does include a filter with a bio sponge intake cover. It does not include a light. If this product chips or cracks, it can be repaired with aquarium-safe epoxy or acrylic. It only has one chamber and does not include baffles.

    Pros
    • Holds over ½ gallon of water
    • Black acrylic backing prevents light bleeding into main tank
    • Includes filter with bio sponge intake cover
    • Chips and cracks can be repaired if needed
    Cons
    • Scratches and breaks easily
    • Prone to leaking
    • Does not include a light
    • Does not have a lid
    • Single chamber without baffles/separators

    Buyer’s Guide

    Things to Consider When Choosing the Right HOB Refugium For Your Tank:
    • Your Intended Use: When choosing a HOB refugium for your tank, take into account what you’re intending to use it for. Some HOB refugiums are better suited for use as a simple breeder box while others are perfect to use as a fully functional sump setup. Some boxes may be better suited for breeding fish as opposed to shrimp, and others are better suited for growing things like algae and amphipods.
    • Your Tank Setup: If your tank is on a strict light cycle and you’re using a HOB refugium to grow high-light algae, then finding a box with darkened backing will help prevent light bleed into your tank. If your tank has cooler water requirements than what you are raising, breeding, or growing in the HOB refugium, then you’ll need to look into adding a heater to warm the water for the refugium without heating the tank.
    • Your Tank’s Glass: If you have a small rimless tank, then a ½ gallon HOB refugium will likely be too heavy and will risk cracking or breaking your tank’s glass. If you have a small tank but it has a sturdy rim, then it will be able to handle a heavier box. Knowing the thickness of your tank’s glass and the width of its rim, if it has one, will help guide you in choosing the perfect HOB refugium for your tank.
    HOB Refugium Options:
    • Refugium box vs kit: If you’re unsure of how to set up a HOB refugium or just want something simple, then purchasing a kit may be the best option for you. A kit should come with all or most of the necessary equipment to get your HOB refugium up and running. If you feel confident in your ability to set it up, or you just have extra equipment like air pumps hanging around that need to be used, then purchasing a HOB refugium box without all the bells and whistles should work perfectly for you.
    • Single chamber vs baffles vs separators: Depending on your desired HOB refugium use, you may want a single chamber box. If you’re wanting to use a HOB refugium as a breeder box for fish that are likely to eat fry, then a box with slotted separators may be perfect for you. Separators can also be a great option if you’re needing to keep multiple fish out of the main tank, like for quarantine, but they are likely to fight in close quarters. Baffles are type of separator that have varying sizes of slots, with some being completely solid, and that can be set at different heights in the box. Baffles are a great way to direct and filter water flow if you’re intending to use a HOB refugium for a sump setup. Baffles can also help protect sensitive plants and corals from water flow.
    • Acrylic vs plastic: Technically, acrylic is a plastic, but all plastics are not created equal. Acrylic is a thick, sturdy plastic that is strong but rigid, making it prone to cracking under too much pressure or with rough handling. Other types of plastic can be thinner and weaker, but more flexible than acrylic, meaning they are at a higher risk of breaking over time, but at a lower risk of cracking like acrylic might. Acrylic is easier to repair than other types of plastics, so a higher-quality HOB refugium will likely be made from acrylic.
    • Clear backing vs darkened backing: How much light do you want passing between the main tank and the HOB refugium? Some boxes have clear backing, meaning that any light you put into the refugium will bleed into the main tank, and vice versa. If you need specific light parameters met within the main tank or the HOB refugium, then a darkened backing will likely meet your tank’s needs better because this backing allows you to keep separate lighting for your main tank and your HOB refugium.
    • Lid vs no lid: HOB refugiums can come with a lid, without a lid, or with a lid that can be purchased separately. This will all be up to your needs for your HOB refugium. A box without a lid is going to have more evaporation than a box with a lid. A box with a lid will have better temperature regulation than a box without a lid. Some people prefer a HOB refugium without a lid for ease of access for maintenance, cleaning, and getting to plants or animals inside if needed. It’s a good idea to take your household into account when choosing whether or not you want a HOB refugium with a lid. Small children may be prone to putting their hands into a box without a lid. Some pets may be prone to attempting to drink from a box without a lid, or even attempting to catch animals inside.
    • Sizes: The size of the HOB refugium you get will depend entirely on your preference, your tank, and your intended usage. The glass and rim of your tank both need to be able to support the weight of whatever HOB items you put on them. If you are wanting to create a sump refugium setup, then you will likely need a large HOB refugium. If you are needing a temporary holding area for acclimating new fish to the tank or for protecting sick fish, then a smaller HOB refugium may meet your needs. HOB refugiums comes in a broad range of sizes, so you have plenty of options to meet your needs.

    When to Use a HOB Refugium When to Use a Quarantine/Secondary Tank
    Acclimating new fish and invertebrates that are coming from quarantine When first bringing new fish and invertebrates home
    Breeding specific colors or types of shrimp When attempting to raise or breed shrimp with predatory fish in the main tank
    Protecting weak or non-contagious sick fish or invertebrates or protecting sensitive plants While treating fish or invertebrates for a contagious illness
    Protecting fry from cannibalism or predation in the tank Raising large numbers of fry or shrimplets
    Growing chaeto, amphipods, copepods, or other food sources Growing large amounts of ground cover plants, like mosses, before adding to the main tank
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    Conclusion

    If you know exactly what you want a HOB refugium for, then these reviews should help you weigh the pros and cons of different products to pick what will best meet your needs. If you aren’t sure what you’re needing, use these reviews to identify what you’re hoping to achieve with your HOB refugium and then pick a product from there.

    The Finnex External Refugium Hang-on Box is the best overall HOB refugium pick because it’s a high-quality product that includes everything you need to get a HOB refugium up and running. The CPR Aquafuge2 Hang-on Refugium is the top premium pick because it’s made from high-quality materials and includes a fully functional pump setup. For the best value, the Marina Hang-on Breeding Box is the top pick, because it’s high-quality, cost-effective, and an especially good pick if you already have a pump and light at home.

    Picking a HOB refugium is overwhelming and learning everything there is to know about getting a HOB refugium working can be confusing, so use this list of products to help make choosing a product easier so you can focus on how you want to set it up to work best for your tank.