Setting up a reef tank requires more equipment than a standard saltwater fish-only system, and significantly more than freshwater. The core list for a functional reef includes: a tank with a drilled overflow and sump, a return pump, a protein skimmer, a refugium or macroalgae section, a heater (and ideally a chiller), high-output lighting, a circulation pump or wavemaker, a refractometer, an RODI unit, test kits, and depending on coral load, a dosing system or calcium reactor. That's the honest answer. Everything on that list earns its place.

This guide walks through each equipment category for a reef tank, what to look for, what to spend, and where hobbyists commonly under-invest and pay for it later.

The Tank and Overflow System

Reef tanks are drilled for a built-in overflow, which allows water to flow down to a sump below the display tank by gravity. This is preferable to a hang-on-back overflow box because it's more reliable and doesn't risk siphon breaks that can flood your floor.

Standard tank sizes for reef setups run from 20 gallons (for a nano reef) to 150+ gallons for larger systems. The most popular reef dimensions include the 40-gallon breeder (36x18x16 inches), the 75-gallon (48x18x20 inches), and the 120-gallon (48x24x24 inches).

AIO (all-in-one) tanks like the Innovative Marine Nuvo series, Red Sea Max, and Waterbox AIO are popular for nano and mid-size reefs. These integrate filtration, lighting, and skimmer into a compact package, simplifying setup for beginners. The Innovative Marine Nuvo 20 and Red Sea Max E-170 are two well-regarded examples.

For custom or larger builds, Reef Savvy, Miracles, and elos make premium rimless tanks. Standard commercial options include Marineland, Aqueon, and Trigger Systems.

The Sump

A sump sits below the display tank and houses most of the equipment. Standard sump design includes:

  • Skimmer section: First section, receives raw overflow water where the skimmer works on it before it passes to the next chamber
  • Refugium/macroalgae section: Middle section, often with a dedicated light (Kessil H380 Spectral Halo, Innovative Marine Cheato Reactor) for growing chaeto or other macroalgae that exports nitrate and phosphate
  • Return section: Last section, where the return pump draws water back to the display tank

Trigger Systems, Reef Savvy, and Bashsea make popular acrylic sumps in common sizes. A sump adds significant total water volume to the system, which improves parameter stability. A 90-gallon display with a 30-gallon sump effectively creates a 120-gallon system that dilutes nutrient swings and temperature fluctuations.

Protein Skimmer

The protein skimmer is the most impactful piece of equipment after the tank itself for maintaining water quality in a reef. It removes dissolved organic compounds before they break down into ammonia and nitrate, improving water clarity and oxygen levels.

Reef Octopus Classic 110SSS: Reliable, well-reviewed, suitable for systems up to 100 gallons. Quiet operation, easy wet/dry adjustment.

Bubble Magus Curve A9: A popular mid-range option for tanks up to 150 gallons with a simple needle wheel impeller design and solid skimmate production.

Nyos Quantum 120: German-engineered, known for ultra-quiet operation and consistent collection. Priced at $350 to $450 but widely praised in serious reef communities.

Skimz Stellar SM163: An option for tanks up to 180 gallons with a space-efficient conical body.

Size your skimmer for a tank 20 to 30 percent larger than yours to avoid running it at maximum capacity continuously.

Lighting

Lighting is where reef tanks diverge most sharply from FOWLR setups. Photosynthetic corals, including most LPS, SPS, and soft corals, require specific light spectra and intensity to host their symbiotic algae (zooxanthellae) and maintain their color.

LED Fixtures

LEDs have become the dominant lighting technology for reef tanks because of their energy efficiency, spectrum tunability, and reduced heat output compared to T5 or metal halide.

Kessil A360X: One of the most respected single fixtures on the market, producing excellent shimmer and coral growth response. Best suited for tanks up to 30 inches wide. Retail around $320 per unit.

Radion XR30 G6 (EcoTech Marine): A premium 30-watt+ array with full spectrum control, integration with VorTech pumps, and a dedicated app for sunrise/sunset programs. Costs $500 to $600 per fixture.

ReefLED 90 (Red Sea): Designed for Red Sea tanks but works well with any equivalent-size system. Excellent out-of-the-box programs, solid coral growth.

AI Hydra 32 HD: A mid-priced option at $230 to $260 with good spectrum coverage and active reef community support for custom light programs.

For a deep comparison of reef-specific UV sterilizer setups that pair well with reef lighting systems, see our Best UV Sterilizer for Reef Tank guide.

Circulation and Flow

Reef corals require significant water movement for feeding, gas exchange, and waste removal. The target flow rate for most reef tanks is 20 to 50 times total tank volume per hour, including both return pump flow and wavemaker output.

Jebao SLW-20 and SLW-30: Programmable wave pumps with multiple flow modes, excellent value at $50 to $100 each. Popular in the hobby for their quiet operation and effective random flow patterns.

VorTech MP10 and MP40 (EcoTech Marine): The premium standard in reef circulation. The wetside motor runs through the tank glass, keeping all electronics on the outside. The MP10 handles smaller tanks; the MP40 moves 3,000+ GPH in larger systems. Expensive ($180 to $300 each) but extremely reliable and quiet.

Tunze Turbelle Nanostream 6020 and 6040: Compact, quiet, and precise. Tunze units last many years with minimal maintenance and are popular in European reef communities.

Heating and Chilling

Reef tanks need stable temperature, typically 76 to 80 degrees Fahrenheit. A titanium heater (Finnex TH-S, Cobalt Neo-Therm Pro) in the sump provides reliable heating without the corrosion concerns of glass heaters in saltwater.

For reef tanks where summer temperatures push the room above 80 degrees or where high-output lighting heats the water, a chiller is necessary. The JBJ Arctica and Teco TK/TC series are the standard choices covered in detail in related guides.

Running an independent temperature controller like the Neptune Apex or Inkbird ITC-306 to manage both heater and chiller gives you automated protection against stuck-on failures from either device.

RODI and Water Quality

Never add tap water to a reef tank. Tap water contains chlorine, chloramine, phosphate, silicate, and other compounds that fuel algae blooms and harm coral.

An RODI unit produces purified water with TDS near zero. The Aquatic Life 100 GPD and BRS 5-Stage RODI systems are popular and well-priced at $100 to $200.

For water quality verification, a handheld TDS meter confirms membrane effectiveness. Replace the RO membrane when output TDS rises above 5 to 10 ppm. Replace DI resin when output TDS reaches 1 ppm or color indicator resin turns yellow.

For more on sourcing clean water inputs and the RODI units rated for reef use, see our Best RODI Unit for Reef Tank guide.

Calcium and Alkalinity Management

Once SPS corals are in the system, calcium and alkalinity demand rises noticeably. The standard management options:

Two-part dosing: BRS Two-Part or ESV B-Ionic delivered by a dosing pump (BRS Dual Pump, Neptune DOS) in multiple small doses throughout the day. Best for tanks under 100 gallons or systems with moderate SPS load.

Kalkwasser: Calcium hydroxide solution delivered via the top-off line. Simpler than two-part, maintains pH well, but less precise and limited in how much calcium/alkalinity it can deliver per day.

Calcium reactor: Dissolves calcium carbonate media using CO2, returning calcium and alkalinity to the tank continuously. Highest setup cost but lowest long-term operating cost. Best for large, heavily stocked SPS systems.

Test Kits and Monitoring

Testing is non-optional in a reef. Minimum test kit coverage: alkalinity, calcium, magnesium, nitrate, and phosphate. Many reef hobbyists also test pH, salinity, and specific gravity.

Salifert test kits are accurate and widely trusted. The Hannah HI772 Checker for phosphate and the Hannah HI755 Checker for alkalinity provide digital readouts that remove color interpretation subjectivity.

Automated monitoring via an Apex, Hydros, or Milwaukee controllers adds real-time pH, temperature, and salinity tracking with alerts for out-of-range conditions.

FAQ

What's the minimum budget for setting up a reef tank? A functional 40-gallon reef setup with used equipment runs $600 to $1,000. Buying new, the same setup costs $1,200 to $2,000. The main cost drivers are lighting ($250 to $500+), the tank itself, the skimmer, and RODI unit. Livestock is a separate and ongoing cost.

What's the easiest reef tank to maintain? A soft coral or LPS-dominated mixed reef is far easier to maintain than an SPS system. Soft corals like Xenia, Kenya Tree, and Leather Corals tolerate parameter swings that would kill SPS. LPS like Hammer, Torch, and Duncan corals are similarly forgiving. Starting with these species builds the water chemistry management skills needed before adding SPS.

How often should I do water changes on a reef tank? 10 to 20 percent monthly is the standard recommendation for established reef tanks. More frequent, smaller changes (5 percent weekly) work equally well and avoid the parameter shock of a large infrequent change. In well-maintained systems with stable parameters, some hobbyists reduce water changes to 10 percent every six weeks. Nitrate and phosphate levels guide the actual frequency needed.

Do I need a controller like Neptune Apex for a reef tank? Not strictly necessary, but extremely useful. A controller like the Neptune Apex ($300 to $600) monitors temperature, pH, salinity, and other parameters, controls outlets for heater, chiller, and lights, and sends alerts when something is out of range. For a system with $2,000 or more in livestock, the insurance value alone justifies the cost. Without a controller, manual checks and independent thermostats provide basic protection.

The Honest Summary

A reef tank is the most equipment-intensive type of aquarium you can set up, and for good reason. Corals are demanding inhabitants that require stable chemistry, intense light, significant flow, and consistent temperature. The equipment listed here isn't manufacturer padding; each piece addresses a specific biological requirement of reef inhabitants. Start with quality basics: a good skimmer, proven LED lighting, a reliable RODI unit, and accurate test kits. Those four investments set the foundation that everything else builds on.