Best Reef Aquarium Sumps and Refugiums (2026)

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 premium picks here. It also ships with fewer equipment holders than the IceCap. For a balanced, USA-made sump at a fair price, though, the RS-75 remains the easy recommendation.

Equipment room is where the IceCap 15 V2 pulls ahead, and CoralVue and Premium Aquatics both list a 15 by 15 by 14 inch footprint rated for tanks of 10 to 80 gallons. That square shape packs more chamber width into a tight cabinet than a long, narrow sump can, which is the main reason to look here rather than elsewhere.

The holders are really the story, because Premium Aquatics lists two 1 inch drains plus an emergency drain holder, a triple probe holder, and a twin heater holder. A 4 inch filter sock holder fits the Klir Di-4 auto-fleece roller. The skimmer section measures 9.4 by 9.6 inches, with a 4.7 by 9.4 inch return zone beside it. Adjustable baffles also let you tune the water level to your gear.

Beyond the spec sheet, the V2 dropped the old freshwater reservoir in order to widen the return chamber. That is a sensible change for most reefers, but it removes a small built-in top-off buffer, so you will need to run an automatic top-off instead.

The compromises here are fairly modest, because the IceCap sump gives you holders rather than the biggest water volume, and its refugium space is tighter than a dedicated refugium cube. For a reef builder who wants every probe, heater, and sock to have a home, though, the IceCap 15 is the most equipment-friendly pick in this lineup.

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 more than the value picks 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.

Bigger systems are where the RS-100 makes the most sense, because it is the larger step-up in the same family as our value pick. Eshopps rates the RS-100 line for roughly 75 to 125 gallon tanks, well above the RS-75, and the manufacturer's listing says it too can run as a refugium, Berlin, or wet/dry setup. More tank means more water demand, and this sump is built to answer it.

The extra size shows up in the numbers, since the RS-100 family lists around 24 by 12 by 16 inches and near 18 gallons of water volume, along with a 7 inch filter sock and a higher flow ceiling than the RS-75. That added buffer holds parameters steadier on a big, heavily stocked reef than a smaller sump can manage.

The part the listing leaves out is that the open-chamber RS-100 leans toward a simple, easy-to-clean layout rather than a maze of baffles. That keeps maintenance quick, but it also means fewer built-in equipment holders than the IceCap, so plan ahead for where your probes and heaters will sit.

The drawbacks come down to size and price, because at over $460 the RS-100 sump is a serious spend, its larger footprint may not fit a smaller stand, and it is plainly overkill for a nano or mid reef. Buy it only when your display is genuinely big, since for a large tank that needs more sump volume, the RS-100 is the natural pick in this lineup.

A refugium-first sump is a different tool, and the Cube Nano is built around that job rather than all-in-one filtration. It is still a compact three-chamber sump, with a skimmer, a refugium, and a return zone, but Eshopps designed it to put the refugium first. We rank it last on the sump rubric on purpose. It is here for reefers who specifically want a refugium, not a do-everything sump.

The whole point is nutrient export. Eshopps uses a dual-channel design that feeds the refugium chamber its own separate, unfiltered water, while the skimmer chamber gets a filter sock first. That separation lets the macroalgae pull nitrate and phosphate out of the water without competing with the skimmer. The refugium chamber runs about 5 by 9 inches, which suits chaeto and a pod population on a nano or small reef.

Worth flagging up front: this is a compact unit rated for 10 to 35 gallon tanks, so it holds modest water and gear. There is room for a nano-scale skimmer and a reactor or two, but not a full bank of probes or a large return pump. Treat the Eshopps refugium as a focused, refugium-led setup rather than the sump for a big system.

The honest trade-offs are scope and value. The Cube Nano costs more than the RS-75 yet skips the Berlin and wet/dry modes, so it does less as a general-purpose sump. It only makes sense if a macroalgae refugium is your actual goal. For pod culture and nutrient export on a small system, though, it is a tidy, purpose-built choice.