Setting up a saltwater reef tank requires a more specific and demanding supply list than any other type of aquarium. At minimum, you need a tank with a sump, a protein skimmer, live rock, a return pump, powerheads, a heater, a high-output LED or T5 light, RO/DI water, quality reef salt, a refractometer, and test kits for pH, ammonia, alkalinity, calcium, and magnesium. That's the functional core. Everything beyond that (dosing systems, calcium reactors, UV sterilizers, refugiums) depends on what coral you're keeping and how precisely you want to maintain water parameters.
This guide covers every supply category for a reef tank build, from the baseline equipment every reef needs to the specialized gear for advanced coral keeping. I'll include specific product recommendations and the numbers that matter for each decision.
The Sump: Why Every Reef Tank Should Have One
The sump sits below the display tank in the cabinet and serves as the hub for all your equipment. Display tank water flows down via an overflow or drilled bulkhead, through the sump where your protein skimmer, heater, and return pump live, then gets pumped back up to the display.
A sump does three critical things:
- Increases total water volume. A 75-gallon display with a 30-gallon sump gives you 105 gallons total. More water volume means slower parameter swings when something goes wrong.
- Hides equipment. Your display tank stays clean and natural-looking while all the ugly gear sits out of sight.
- Allows a refugium. A section of your sump with lights and chaeto macro algae absorbs nitrates and phosphates naturally, reducing your chemical maintenance.
DIY sumps (modified acrylic tanks with baffles) work well, but brand options like the Trigger Systems Cube 34 ($200-250) and the CPR AquaFuge 2 provide pre-made solutions that fit most standard cabinet spaces.
Protein Skimmers for Reef Tanks
The protein skimmer is the most important piece of equipment in a reef system. It exports dissolved organic compounds before they break down into ammonia and nitrates that stress coral.
Reef tanks run at much lower nutrient levels than fish-only systems. Most SPS (small polyp stony) coral keepers target nitrate under 10 ppm and phosphate under 0.1 ppm (ideally 0.03-0.05 ppm). Skimmers are the first line of offense against nutrient accumulation.
Always size up. A skimmer rated for 150 gallons on a 90-gallon reef is correct. Overrated skimmers don't cause harm. Undersized ones leave dissolved organics in the water.
Reef Octopus Classic 110-INT: In-sump skimmer rated for tanks up to 100 gallons. The gold standard in the $120-130 price range. Consistent skimmate, easy to adjust, reliable needle wheel pump.
Reef Octopus Classic 152-INT: Handles up to 150 gallons. About $170. Step up to this if you're running a 75-100 gallon display with heavy coral or fish loading.
Bubble Magus Curve 5: A popular budget option at $110-120, rated for 130 gallons, realistically handles 75-85 gallons in a reef context.
Vertex Omega 150: Premium skimmer for larger systems (up to 200 gallons). Around $350. Used in high-end builds with SPS coral and large fish populations.
In-sump models are almost always better than hang-on-back skimmers for reef tanks. Adjust the water level around the neck of the skimmer with the included valve until you're producing wet, dark green or black skimmate. Clear or very light skimmate means the skimmer is running too dry.
Lighting for Reef Tanks
Coral are photosynthetic through symbiotic algae called zooxanthellae. Get lighting wrong and your coral bleaches or slowly dies. Get it right and coral grows, colors up, and reproduces.
Understanding PAR
PAR (photosynthetically active radiation) measures the light intensity that photosynthetic organisms actually use. It's the number that matters for coral placement and fixture selection, not watts or lumens.
General PAR targets: - Soft coral (mushrooms, zoanthids, leathers): 50-150 PAR - LPS coral (hammers, torches, brains, frogspawn): 75-200 PAR - SPS coral (Acropora, Montipora, Seriatopora): 200-450 PAR
LED Fixtures
AI Prime HD ($185-200): Best small reef LED on the market for tanks up to 24" x 24". Runs the Aquaillumination app, has sunrise/sunset programming, and covers the full spectrum including deep blue and UV. Perfect for nano and mid-size reef tanks.
Kessil A360WE ($400): Single-point LED with exceptional color rendering. Covers up to a 36" x 30" footprint at medium height. Used in both SPS and mixed reef tanks.
Radion XR15 G6 Pro ($550): High-end fixture used in SPS-dominated systems. Includes EcoSmart programming and delivers PAR levels high enough for even demanding Acropora species.
AI Hydra 32 HD ($350): Strong performer for tanks up to 36" x 24". A step down in price from the Radion but delivers comparable performance for most mixed reef setups.
For tanks over 48" wide, plan on 2-3 fixtures or look at T5 hybrid setups (T5 fluorescent lamps over LEDs) which provide more even coverage across large footprints.
Water Preparation: RO/DI and Salt Mix
Tap water is unsuitable for reef tanks. Even low concentrations of phosphates, silicates, chloramines, and heavy metals stress coral and fuel nuisance algae. An RO/DI system is the standard solution.
RO/DI Systems
The BRS 4-Stage RO/DI Deluxe ($180-220) handles most home setups. It removes 99%+ of TDS (total dissolved solids) and includes a sediment prefilter, carbon block, RO membrane, and DI resin cartridge. Output water should read 0-5 PPM TDS on a meter; anything above 10 PPM indicates exhausted media.
Replace the DI resin when it changes from a blue/green color to amber. Replace the RO membrane every 1-3 years depending on source water quality.
For the best RODI unit for reef tank options, that guide covers the major brands with pricing and flow rate comparisons.
Salt Mix Selection
Red Sea Coral Pro Salt ($55-65 for 55 gallons): The benchmark reef salt. High calcium (440-460 ppm mixed), elevated alkalinity (12-13 dKH), and consistent batch-to-batch quality. The preferred salt for SPS-dominated systems because it reduces how much supplemental dosing you need early on.
Instant Ocean Reef Crystals ($35-45 for 50 gallons): A strong mid-range reef salt. Slightly lower calcium and alkalinity than Coral Pro but adequate for mixed reef and LPS setups.
Target salinity: 1.025-1.026 specific gravity (35 ppt). Measure with a refractometer, not a swing arm hydrometer. The Milwaukee MA887 refractometer ($30) is the standard recommendation.
Water Testing for Reef Tanks
Reef tanks require a more comprehensive testing regime than freshwater. You need to track not just ammonia and nitrate, but the major elements that coral extract from the water constantly.
The essential reef test kit list:
| Parameter | Target | Test Kit |
|---|---|---|
| Ammonia | 0 ppm | API Saltwater Master Kit |
| Nitrite | 0 ppm | API Saltwater Master Kit |
| Nitrate | 0-10 ppm (SPS), 0-20 (LPS) | Salifert Nitrate |
| Phosphate | 0.03-0.1 ppm | Hanna Checker HI713 |
| Alkalinity | 8-10 dKH | Salifert Alkalinity |
| Calcium | 400-450 ppm | Salifert Calcium |
| Magnesium | 1250-1350 ppm | Salifert Magnesium |
| pH | 8.1-8.3 | Digital probe or Hanna checker |
| Salinity | 1.025-1.026 SG | Refractometer |
The Salifert test kits are the industry standard for accuracy in these ranges. Hanna Checkers (digital colorimeters) are worth the investment for phosphate and alkalinity testing because they're more accurate than color comparison reagent kits in the critical low ranges.
A UV sterilizer isn't on every reef tank but can help with parasite and bacteria control. See our guide on the best UV sterilizer for reef tank for models and sizing.
Dosing and Element Supplementation
Coral consume calcium and alkalinity rapidly as they build their calcium carbonate skeletons. A growing SPS reef can deplete these parameters measurably in 24 hours. You need a way to replenish them.
Two-part dosing: The simplest method. Two separate solutions (Part A: alkalinity buffer, Part B: calcium chloride) get dosed in equal amounts. BRS 2-Part is the most widely used. Dosing pumps like the Kamoer FX-STP2 or BRS Precision Dosing Pump automate the process once you dial in your depletion rate.
Kalkwasser: Calcium hydroxide powder mixed with RO water and dripped slowly into the sump via a dosing pump or gravity dripper. Replenishes both calcium and alkalinity simultaneously and raises pH. The simplest low-cost solution for tanks with moderate coral growth.
Calcium reactor: For high-SPS systems with large coral populations. Recirculates sump water through a chamber of calcium carbonate media with injected CO2, dissolving the media to replenish calcium and alkalinity in the most stable, natural way. Complex to set up but extremely stable once dialed in. Appropriate for mature systems.
For most beginning and intermediate reef tanks, two-part dosing with a pair of dosing pumps handles everything cleanly.
FAQ
How much does it cost to set up a 75-gallon reef tank?
A basic but properly equipped 75-gallon reef build costs $1,500-2,500 in equipment before livestock and coral. That includes: tank ($200-300), stand ($150-200), sump ($100-200), protein skimmer ($130-150), return pump ($80-120), powerheads ($60-100), heater ($30-40), LED light ($180-400), RO/DI system ($180-220), salt and rock ($200-300), and test kits ($100-150). Coral and fish are separate costs.
Can I keep coral without a sump?
Yes, but it's significantly harder. Without a sump you're limited to hang-on-back skimmers (less effective), have less total water volume, and can't easily run a refugium. Many successful small reef tanks run sumpless with a quality HOB skimmer and careful maintenance. It works best for tanks under 30 gallons with soft coral and LPS.
How often do I need to test water in a reef tank?
During the first 3-6 months: test pH, ammonia, nitrite, and nitrate weekly. Once the tank is established, test alkalinity 2-3 times per week (especially once you add coral), calcium and magnesium once per week, and nitrate and phosphate weekly. You can scale back once parameters are stable and you've established a reliable dosing routine.
Do I need a UV sterilizer for a reef tank?
Not mandatory, but useful. UV sterilizers reduce free-floating bacteria and parasites (including ich) and can prevent disease from spreading through the water column. They're most valuable in tanks with fish (particularly tang species that are ich-prone) rather than coral-only systems. A properly sized UV sterilizer also clears green water outbreaks quickly. Size at 1-2 watts per gallon flow rate through the unit.
Wrapping Up
A successful reef tank comes down to stable water parameters more than any other single factor. Buy quality where it matters: a properly sized skimmer, a reliable RO/DI system for water preparation, and test kits you'll actually use regularly. The lighting matters enormously for coral, so don't underbuy on that. Then be patient with cycling and adding livestock. Most reef tank failures happen in the first 60 days from rushing the process, not from missing equipment.