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Best Reef Aquarium Sumps and Refugiums (2026)

The Eshopps RS-75 is the three-chamber sump we'd reach for first on most nano-to-mid reef tanks, pairing a refugium/Berlin/wet-dry layout with a fair price. The Fiji Cube Fiji-20 is the premium full-cast-acrylic build for a mid-to-large reef, with more water volume and more built-in equipment holders, so match the sump to your tank size, gear, and cabinet space rather than chasing the biggest box.

By Nick Miles Β· Updated August 12, 2026 Β· ~12 min read

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Best Reef Aquarium Sumps and Refugiums (2026)
Part of:Aquarium Filtration & Maintenance Systems for Clear, Healthy Water (2026 Guide)

Evidence at a Glance

Eshopps RS-75 Reef Sump (Refugium / Berlin / Wet-Dry)

A three-chamber reef sump the manufacturer lists as refugium, Berlin, or wet/dry capable, with a 20 by 10 by 16 inch footprint rated for 10 to 75 gallon tanks β€” the balanced value pick for most nano-to-mid reefs.

Sources: Eshopps product page, Bulk Reef Supply product page, Amazon listing

Verified Jun 25, 2026

Fiji Cube Fiji-20 Advanced Reef Sump 2nd Gen

A full cast-acrylic sump with a top support brace that Bulk Reef Supply lists at 20 gallons for 60 to 100 gallon tanks, with a floss box, filter sock, dosing holes, and an ATO float-valve holder β€” the premium, refugium-ready build.

Sources: Fiji Cube product page, Bulk Reef Supply product page, Amazon listing

Verified Jun 25, 2026

The Short Answer

The Eshopps RS-75 is the reef sump to buy first for most nano-to-mid tanks, a flexible three-chamber box that Eshopps lists at 20 by 10 by 16 inches and rates for 10 to 75 gallon tanks. It can run as a refugium, Berlin, or wet/dry filter, which is why chamber layout matters more than raw size. A sump itself is just a second tank below your display that hides the skimmer, heater, return pump, and a refugium while adding steadying water volume. The Fiji Cube Fiji-20 is the premium cast-acrylic build for a mid-to-large reef, with a full top support brace, 20 gallons of sump water, and holders for a heater, probes, dosing lines, and an automatic top-off float valve. Match the sump to your tank size, your equipment, and the space inside your cabinet.

Every product on this list has been scored against the PetPal Gear Score, a weighted composite of expert consensus, observed effectiveness, animal safety, long-term durability, and value. Review method: Editorial synthesis of manufacturer and retailer specifications consulted directly. We read the Eshopps and Fiji Cube product pages, plus the Bulk Reef Supply and Premium Aquatics listings, and each spec is quoted from the page it came from. PetPalHQ did not test these sumps first-hand and does not run a testing lab. The ReefSump Score is a composite of published specifications and expert and hobbyist consensus rather than a measurement, and the rank reflects best-fit use case instead of raw score order. A higher-ranked pick is the better fit for its scenario, not necessarily the higher score. Price is deliberately not a scoring factor, so the premium pick is neither rewarded nor penalized for cost on the rubric; the price caveats instead live in the cons, the verdicts, and the skip-it section.. Synthesized from 4+ expert sources.

A reef aquarium sump is a second tank that sits in the cabinet below your display. It does the quiet, unglamorous work of filtration. The skimmer, heater, return pump, and a refugium all live down there, out of sight of the show tank. A sump also adds water volume to the system, and more water means steadier temperature, salinity, and chemistry. A refugium goes a step further by growing macroalgae that pulls nitrate and phosphate out of the water. The catch is that a sump is mostly a box of chambers, so the layout of those chambers β€” and the quality of the acrylic and baffles β€” matters far more than the raw gallon rating on the label.

The picks below are editorial synthesis. PetPalHQ does not run a testing lab. Every product here was chosen by reading manufacturer and retailer specifications from Eshopps and Fiji Cube. We also read the Bulk Reef Supply and Premium Aquatics listings and weighed reefkeeping consensus. Where sources framed things differently, we deferred to chamber layout, build quality, and a leak-free track record over a bigger gallon number.

This guide is the sump-and-refugium companion to our broader filtration and maintenance hub. Rank reflects best-fit use case, value all-rounder and premium build, rather than raw score order. The right pick is the one that matches your tank size, equipment, and cabinet space, not simply the highest number.

Head-to-Head Comparison

FeatureEshopps RS-75 Reef Sump (Refugium / Berlin / Wet-Dry)Fiji Cube Fiji-20 Advanced Reef Sump 2nd Gen
Best-fit use caseAll-round 3-chamber value sumpPremium cast-acrylic build
Footprint (L x W x H)20 x 10 x 16 in (Eshopps/BRS)20 x 15 x 16 in (BRS)
Rated tank size10-75 gal60-100 gal
Sump water volume~12 gal (Eshopps/BRS)20 gal (BRS)
Mechanical filtration4 in filter sockFloss box + 4 in sock (included)
Listed price at time of check$262.85$404.99
Check priceAmazonAmazon
9.3/10Β· BEST OVERALL

Eshopps Eshopps RS-75 Reef Sump (Refugium / Berlin / Wet-Dry)

𝕏↑f
Eshopps RS-75 Reef Sump (Refugium / Berlin / Wet-Dry)

$262.85

  • Three-chamber design that runs as a refugium, Berlin, or wet/dry filter (manufacturer listing)
  • 20 by 10 by 16 inch footprint rated for 10 to 75 gallon tanks (Eshopps/BRS)
  • Built-in 4 inch filter sock for mechanical pre-filtering
  • 6 by 9.5 inch skimmer chamber and 5 by 9.5 inch return chamber (Eshopps/BRS)
  • Around 12 gallons of sump water volume and a 600 GPH max flow (Eshopps/BRS)
Check price

The Eshopps RS-75 is the sump we would point most reefers toward first, and it earns the top slot on overall balance rather than on any single standout spec. Eshopps and Bulk Reef Supply both list a 20 by 10 by 16 inch footprint rated for tanks of 10 to 75 gallons. The manufacturer's listing says it can run as a refugium, a Berlin-style sump, or a wet/dry filter. That configuration flexibility is the main reason to start here instead of with a single-purpose box.

The chamber layout is the real draw. Water enters one chamber, passes a 4 inch filter sock, and then splits toward the skimmer and refugium zones before it reaches the return pump. Eshopps lists a 6 by 9.5 inch skimmer chamber alongside a 5 by 9.5 inch return chamber, and a 600 GPH maximum flow gives most nano-to-mid reef tanks plenty of room to work.

One thing the listings skip is that a sump is only ever as quiet as the plumbing you connect to it, so plan to dial in the drain and add a baffle sponge if you start chasing micro-bubbles. The included filter sock is also a wear item, which means you should rinse or replace it on a regular schedule rather than leaving it to clog.

The downsides are real, too. At roughly 12 gallons of water volume, the RS-75 sump buffers a smaller system than the 20 gallon Fiji-20. It also ships with fewer built-in equipment holders, since the Fiji-20 adds a removable heater holder, a probe holder, dosing holes, and a float-valve mount that the RS-75 leaves to you. For a balanced, USA-made sump at a fair price, though, the RS-75 remains the easy recommendation.

What We Love

  • Flexible three-chamber layout runs as refugium, Berlin, or wet/dry
  • Fair price for a USA-made reef sump
  • Sensible footprint fits most nano-to-mid cabinets
  • Included 4 inch filter sock handles mechanical filtration
  • Proven RS-family design with a solid leak track record

What Could Be Better

  • Only about 12 gallons of water volume, less buffer than the 20 gallon Fiji-20
  • Fewer built-in equipment holders than the Fiji-20
  • Single 1 inch drain, so plumbing must be dialed in for quiet flow
  • Refugium zone is modest compared with a purpose-built refugium sump

The Verdict

The balanced, USA-made sump to buy first for most nano-to-mid reef tanks, because the RS-75 pairs a flexible three-chamber layout with a fair price, so dial in the drain and pick the filtration style that suits your system.

Sources

  • Eshopps: Dimensions 20x10x16 in; recommended tank size 10-75 gal; total water volume 12 US gallons; skimmer chamber 6x9.5 in; return pump chamber 5x9.5 in; 4 in filter sock; max flow 600 GPH
  • Bulk Reef Supply: 20 L x 10 W x 16 H in; recommended 10-75 gallons; 12 US gallons total water volume; one 4-inch filter sock included; max flow rate 600 GPH; 1x 1 in bulkhead drain
9.2/10Β· BEST PREMIUM BUILD

Fiji Cube Fiji Cube Fiji-20 Advanced Reef Sump 2nd Gen

𝕏↑f
Fiji Cube Fiji-20 Advanced Reef Sump 2nd Gen

$404.99

  • Full cast acrylic with a full top support brace against bowing (Fiji Cube/BRS)
  • 20 by 15 by 16 inch sump holding 20 gallons, rated for 60 to 100 gallon tanks (BRS)
  • Water level adjustable from 5 to 12 inches across the chambers (Fiji Cube)
  • Interchangeable filter floss box and 4 inch filter sock, sock included (BRS)
  • Removable heater holder, probe holder, dosing holes, and ATO float-valve holder (BRS)
Check price

Build quality is the central case for the Fiji-20, because Fiji Cube and Bulk Reef Supply both describe full cast acrylic with a full top support brace that stiffens the tank and fights long-term bowing. A polycarbonate cover cuts noise and evaporation as well, and that cast-acrylic shell is the reason this sump sits at the premium end of the lineup.

The feature set runs deep, since BRS lists a 20 by 15 by 16 inch sump holding 20 gallons of water and rated for 60 to 100 gallon tanks. The water level adjusts from 5 to 12 inches across the skimmer, refugium, and equipment zones. You also get an interchangeable floss box and a 4 inch filter sock, with the sock included. A removable heater holder, probe holder, dosing holes, and an auto-top-off float valve holder round it out.

A detail the spec page omits is that all of that bundled gear means more to set up on day one. The float-valve holder still needs your own ATO pump and controller, and refugium-ready does not mean refugium-stocked, so you still supply the macroalgae and the light.

The honest trade-offs come down to price and size, because the Fiji-20 costs well over a hundred dollars more than the RS-75 and eats a larger footprint, and a nano tank simply does not need 20 gallons of sump water. For a mid-to-large reef that wants a premium, refugium-ready build, though, the Fiji Cube sump is the one to beat.

What We Love

  • Full cast acrylic and top brace resist long-term bowing
  • Large 20 gallon water volume steadies a bigger reef
  • Bundled floss box, filter sock, and holders for fast setup
  • Adjustable 5 to 12 inch water level across the chambers
  • Refugium-ready zone for macroalgae and copepods

What Could Be Better

  • Premium price, well above the RS-75
  • Large 20 by 15 by 16 inch footprint needs a big stand
  • More bundled gear means more to install on day one
  • ATO float-valve holder still needs your own pump and controller

The Verdict

The premium, refugium-ready build for a mid-to-large reef, because the Fiji-20 wins on cast-acrylic quality and bundled gear, so long as you budget for the higher price and the larger footprint.

Sources

  • Fiji Cube: Full cast acrylic with full top support brace; interchangeable filter socks or filter floss holder; water level in the sump is adjustable from 5 in to 12 in; refugium compartment to cultivate copepods; polycarbonate sump cover and lid included
  • Bulk Reef Supply: 20 L x 15 W x 16 H in; 20 gallon water capacity; recommended 60-100 gallons; full cast acrylic with full top support brace; two 4 in holders for floss box and filter sock; removable heater holder, test probe holder and dosing holes; removable auto top-off float valve holder; skimmer 14.2x8.1, refugium 5.2x5.8, return 8.1x5.8

How We Score

Formula

ReefSump Score = (Chamber & Refugium Layout Γ— 0.30) + (Acrylic & Baffle Quality Γ— 0.25) + (Equipment Compatibility Γ— 0.20) + (Volume vs Footprint Γ— 0.15) + (Leak Record Γ— 0.10)

Score Factors

Chamber & Refugium Layout Β· 30%
This factor looks at how the sump splits flow into the skimmer, refugium, and return zones, and it carries the highest weight because the layout decides what the sump can actually run. A good design keeps each chamber separate so the jobs do not fight one another, and a real refugium zone lets macroalgae export nitrate and phosphate. The ReefSump Score is a composite of manufacturer specifications and expert consensus rather than a measurement, since PetPalHQ does not run a testing lab.
Acrylic & Baffle Quality Β· 25%
This factor covers the build material and the baffle design, because cast acrylic and a top brace resist bowing over years of continuous use. Clean baffles trap micro-bubbles before they reach the return pump, and adjustable baffles let you tune the water level to your gear. A sump with better acrylic and smarter baffles earns a higher mark here than a thinner, fixed-baffle box.
Equipment Compatibility Β· 20%
This factor measures how much room and how many holders the sump gives your gear, which includes space for a skimmer, heater, return pump, and reactors. It also weighs the probe holders, dosing holes, an automatic top-off mount, and a filter sock or floss tray. A sump that provides more homes for your equipment scores higher than one that leaves your gear with nowhere to sit.
Volume vs Footprint Β· 15%
This factor balances how much water and capacity you get against the cabinet space the sump eats, because more water buffers temperature, salinity, and chemistry while a large footprint may not fit your stand. It rewards a sump that delivers useful volume without wasting space, since the biggest box is not helpful if it cannot pass through the cabinet door.
Leak Record Β· 10%
This factor weighs seam quality and the brand's track record for staying dry, because a sump runs for years under your tank and often goes unattended for long stretches. Strong seams and a clean history matter more than they first appear. Price is excluded from the rubric, so the premium and larger picks are neither rewarded nor penalized for cost.
RankProductScore
#1Eshopps Eshopps RS-75 Reef Sump (Refugium / Berlin / Wet-Dry)9.3
#2Fiji Cube Fiji Cube Fiji-20 Advanced Reef Sump 2nd Gen9.2

When NOT to Buy

Skip a sump entirely if your tank is a small all-in-one with no overflow, because adding one would mean drilling the tank or hanging an overflow box that you may not want. Skip the Fiji-20 if you run a nano or mid reef, since its 20 by 15 by 16 inch footprint may not fit your stand and you would pay for water volume you do not need. On a display under 60 gallons the RS-75 does the same job for less money. Skip any sump if you are not ready to plumb a drain and tune the water level, because a rushed install is how leaks and bubble noise usually start. And measure your cabinet first, because the best sump is the one that actually fits the space you have. For where a sump fits the wider system, see our aquarium filtration and maintenance hub.

Frequently Asked Questions

What does a reef sump actually do, and do I need one?
A sump is a second tank below your display that holds your filtration gear and your extra water, so it hides the skimmer, heater, and return pump while adding volume that steadies temperature and chemistry. A refugium chamber can also grow macroalgae that exports nitrate and phosphate. You do not strictly need one if your tank is a small all-in-one, but once a reef grows, a sump makes filtration, top-off, and dosing far easier to run and to hide out of sight.
What size sump should I get for my tank?
You should match the sump to your display and your cabinet, in that order. The layout only helps if the box actually fits. The Eshopps RS-75 suits tanks around 10 to 75 gallons, while the Fiji-20 is rated for 60 to 100. Always measure the inside of your stand first, since a sump that will not pass the cabinet door is the wrong sump no matter how good its chambers are.
What is a refugium, and is it worth running?
A refugium is a calm chamber where macroalgae such as chaeto grows under a small light, and as that algae grows it pulls nitrate and phosphate out of the water, which is natural nutrient export. It also shelters the copepods and amphipods that feed your fish and corals. For most reefs it is worth running, and both sumps here fold a refugium zone into a general-purpose box: the RS-75 can be configured as a refugium outright, and the Fiji-20 has a dedicated refugium compartment Fiji Cube sizes for copepod culture.
Why does chamber layout matter more than sump size?
Chamber layout matters more because it decides what the sump can actually run. A good design keeps the skimmer, refugium, and return pump in separate zones so they do not fight each other. Baffles trap micro-bubbles before water reaches the return pump, and probe and heater holders keep your gear both tidy and safe. A huge sump with a poor layout is harder to use than a smaller one with smart chambers, because size only adds water buffer while layout adds real function.
Are acrylic sumps prone to leaking?
A well-built acrylic sump rarely leaks, which is exactly why seam quality and brand track record carry weight in the rubric here. Cast acrylic with a top brace resists bowing over years of use, and the real leak risk is usually the plumbing rather than the box itself. Most drips start at a loose bulkhead, a bad union, or a sock overflow instead of a failed seam, so test a new sump with fresh water for a full day before you trust it on a stocked reef.
Can I add a sump to a tank that isn't reef-ready?
Sometimes you can, but it takes real work, because a sump needs water to drain down and then pump back up, so the tank requires either a drilled overflow or a hang-on overflow box. A reef-ready tank already has the holes and an overflow built in, while a standard tank must be drilled or fitted with an external overflow, which adds both cost and some risk. If you are not comfortable plumbing a drain, plan that step carefully before you buy any sump on this page.

Bottom Line

Get the Eshopps RS-75 for most nano-to-mid reef tanks, because its three-chamber layout runs as a refugium, Berlin, or wet/dry filter at a fair price.

Get the Fiji-20 for a premium, refugium-ready build on a mid-to-large reef, because the full cast acrylic and the top brace are what you are paying extra for.

Both boxes fold a refugium zone into a general-purpose sump, so if macroalgae export is the whole point, budget for a refugium light and the chaeto to put under it.

Whatever you choose, remember that layout beats size, so measure your cabinet, plumb the drain carefully, and tune the water level before you trust the sump overnight.

Sources & Methodology

Methodology

ReefSump Score = (Chamber & Refugium Layout Γ— 0.30) + (Acrylic & Baffle Quality Γ— 0.25) + (Equipment Compatibility Γ— 0.20) + (Volume vs Footprint Γ— 0.15) + (Leak Record Γ— 0.10)

Expert review sources

  • Eshopps β€” RS-75 Oceana reef sump product page and specifications
  • Fiji Cube β€” Fiji-20 Advanced Reef Sump 2nd Gen product page and specifications
  • Bulk Reef Supply β€” RS-75 and Fiji-20 sump product listings and BRStv spotlights
  • Premium Aquatics β€” Eshopps sump product listings

Community sources

  • Reefkeeping hobbyist consensus that chamber layout, quiet baffles, and a leak-free seam matter more than raw sump size, and that the sump should be sized to fit the cabinet first

Prices and specs verified June 25, 2026.

About the author

Nick Miles is the chief editor of PetPalHQ. The picks above are editorial synthesis of manufacturer and retailer specifications and published expert and hobbyist consensus β€” PetPalHQ does not run a testing lab and did not test these products first-hand. The ReefSump Score is a composite of expert opinion and published specs, not a measurement, and rank reflects best-fit use case rather than raw score order. Sources are cited by name throughout.

PetPalHQ is a participant in the Amazon Services LLC Associates Program. We may earn commissions from qualifying purchases β€” at no extra cost to you.