Building a reef tank requires a specific set of equipment, and knowing what to buy before you spend money saves you from costly mistakes. Your reef aquarium supply list comes down to six core categories: filtration (including a protein skimmer and live rock), lighting, water movement, a quality RO/DI water system, a heater, and test kits. Get those right and you have a functional reef. Everything else is refinement.
Reef keeping has a reputation for being complicated, but most of the complexity comes from skipping fundamentals. This guide walks through every piece of gear you'll need, explains what to prioritize when budget is tight, and flags the items that seem optional but actually matter more than people expect.
The Non-Negotiables: Core Filtration
Reef tanks run on biological filtration. Unlike freshwater setups where a hang-on-back filter handles most of the work, saltwater reefs need multiple filtration layers working together.
Protein Skimmer
A protein skimmer pulls dissolved organics out of the water column before they break down into nitrate. This matters enormously in a reef because coral is sensitive to nitrate and phosphate levels that fish would barely notice.
For tanks up to 75 gallons, the Reef Octopus Classic 100-INT runs around $170 and handles the job reliably. The Bubble Magus Curve A5 is another solid option in that price range. For larger tanks (100 gallons plus), look at the Reef Octopus Classic 150-INT or the Bubble Magus Curve A9.
Sizing matters more than brand. An undersized skimmer in a heavily stocked reef will always struggle, no matter how well it's built.
Live Rock and Biological Filtration
Live rock does the heavy biological lifting in a reef. You want roughly 1 to 1.5 pounds per gallon of display tank volume as a starting point, though quality matters more than weight. Real aquacultured live rock from a reputable vendor colonizes faster than dry rock and introduces beneficial microfauna.
Some reefers run a refugium behind the main display, a small separate chamber with macroalgae like Chaeto that absorbs nutrients. It's not strictly required, but it makes a real difference in tanks with high bioloads.
Lighting for Coral
Lighting is where reef tank costs escalate fast. Coral needs light for photosynthesis, but the spectrum and intensity requirements vary significantly by coral type.
Soft Corals and LPS
Leather corals, mushrooms, Zoanthids, and most LPS (large polyp stony) corals do well under moderate light. The Kessil A160WE Tuna Blue ($170) or the AI Prime HD ($250) cover a 24-inch cube comfortably for this category.
SPS and Demanding Corals
Small polyp stony corals like Acropora and Montipora want high intensity and the right spectrum. The AI Hydra 32 HD ($350) or the Kessil AP9X ($700) are go-to choices at the higher end. For a full 4-foot reef, you'll often need two fixtures side by side.
Budget for at least $300 to $700 in lighting for a properly lit reef tank. Going cheaper usually means replacing the light in 18 months when your corals stall.
Water Movement: Powerheads and Wave Makers
Reef corals evolved on ocean reefs where water moves constantly. Stagnant spots lead to dead tissue and algae. You want chaotic, multi-directional flow rather than a single stream blasting one area.
The Jebao SLW-10 ($45) and the Maxspect Gyre XF230 ($150) are both popular for creating reef-appropriate flow without spending a fortune. The Gyre design in particular produces a broad sheet of water rather than a point stream, which eliminates dead zones more efficiently.
Aim for a total flow rate of 20 to 40 times your tank volume per hour. A 50-gallon reef wants 1,000 to 2,000 GPH of water movement total, spread across multiple powerheads.
RO/DI Water: The Foundation of a Stable Reef
Tap water contains chlorine, chloramine, phosphates, silicates, and nitrates that accumulate over time in a reef. You need to start with pure water for both top-offs and water changes.
An RO/DI unit is not optional for serious reef keeping. The BRS 4-Stage RO/DI System ($160) is the entry-level standard that most hobbyists start with. If you're running a larger system with frequent water changes, the BRS 6-Stage ($220) adds extra capacity and protection. Our guide to the best RODI units for reef tanks covers the top options in detail.
TDS (total dissolved solids) should read 0 from your RO/DI output. Anything above 10 is a problem. Keep a cheap inline TDS meter on your system and replace membranes and DI resin on schedule.
UV Sterilization: Optional but Valuable
UV sterilizers kill free-floating bacteria, parasites, and algae spores that pass through the unit. They won't cure an existing ich outbreak, but they reduce the load of pathogens in the water column and keep algae blooms from getting started.
For a reef under 75 gallons, the Aqua Ultraviolet Advantage 8W ($130) or the Emperor Aquatics 8W UV ($160) are well-built options that don't starve coral-beneficial microbes the way undersized, too-powerful units can. Matching UV wattage to tank volume is important. Check our best UV sterilizers for reef tanks guide for full size recommendations.
Heater and Temperature Control
Reef corals are comfortable between 76 and 80 degrees Fahrenheit, with stability mattering more than the exact number. Temperature swings of more than 2 degrees per day stress coral and make them susceptible to bleaching.
The Eheim Jager 150W ($40) is reliable for tanks up to 50 gallons. For larger systems, two smaller heaters are better than one big one because if one fails, the tank doesn't crash immediately. Controllers like the InkBird ITC-306A ($30) add a thermostat layer that cuts power if the heater malfunctions and runs hot.
Testing and Chemistry
You cannot skip testing in a reef. Alkalinity, calcium, and magnesium are the three parameters coral uses to build skeleton, and they deplete steadily in an active reef.
The Salifert test kits for alkalinity ($12), calcium ($14), and magnesium ($17) are accurate and widely used. The Red Sea Reef Foundation Pro test kit bundle covers all three together for around $50 and is worth the convenience.
For ongoing dosing, two-part solutions like BRS 2-Part or a calcium reactor keep levels stable as the tank matures. Automated dosing pumps like the Kamoer X4 ($150) remove the manual work once you've calculated your daily consumption rate.
FAQ
How much does it cost to set up a reef aquarium? A basic 40-gallon reef with entry-level versions of all necessary equipment runs $800 to $1,200 not counting the tank itself. A high-end 75-gallon reef with quality lighting, a protein skimmer, and automated dosing can reach $3,000 to $5,000 before livestock.
Can I use tap water in a reef tank? No. Tap water contains chloramine, phosphates, nitrates, and silicates that build up over time and cause algae problems and coral stress. An RO/DI unit producing 0 TDS water is essential.
What order should I buy reef equipment in? Start with tank, stand, sump/filtration, and heater. Then add lighting, powerheads, and RO/DI. Run the tank fishless for four to six weeks to cycle it before adding livestock. Coral and livestock come last.
Do I need a sump for a reef tank? Not strictly required, but a sump makes hiding equipment much easier and adds water volume, which increases stability. Most reefers running serious setups use a sump with a protein skimmer, return pump, and refugium chamber.
What to Buy First
If you're staring at a blank wall where your reef tank will go, start with the tank, a quality sump, and a protein skimmer. Get those sized correctly and the rest of the equipment decisions become much clearer. Buy RO/DI early so you have pure water ready when the tank cycles. Lighting can follow once you know what corals you actually want to keep.
Reef keeping rewards patience more than money. A modest setup with consistent water changes, stable parameters, and quality live rock will outperform a heavily equipped tank that gets neglected.