The supplies you need for a saltwater aquarium fall into two groups: what you need before a single drop of water goes in, and what you add as the tank matures. The first group includes a tank and stand, a protein skimmer, a heater, a circulation pump, salt mix, an RO/DI water filter, and a refractometer. Without these, you can't run a stable system. Everything else, from auto top-off units to dosing pumps to specialized lighting, comes later and depends on what you're keeping.
Getting overwhelmed by the supply list is one of the main reasons people quit saltwater before they really get started. This guide organizes everything by priority so you know what to buy first and what to add over time.
Tier 1: Supplies You Need Before Anything Lives in the Tank
The Tank and Stand
Tank size determines almost everything else. Larger tanks are more forgiving of mistakes because more water volume dilutes chemistry errors. A 40-gallon breeder or a 55-gallon tank is a better starting point than a 10-gallon nano if you're new to saltwater.
The stand must be rated for the tank's filled weight. Water weighs 8.34 pounds per gallon. A 75-gallon tank with a 20-gallon sump holds about 95 gallons when you account for rock and equipment displacement, which is still close to 800 pounds of water alone, before the tank, stand, and live rock. Metal stands (Metal stand from Imagitarium or Aqueon) or solid wood furniture stands handle this safely. Particle board stands are a failure risk.
Protein Skimmer
A protein skimmer removes dissolved organic compounds before they break down into nitrate and phosphate. For any saltwater tank with fish, it's the most impactful piece of filtration you'll run. Size it for at least 1.5 times your system volume. The Bubble Magus Curve A9 handles 100 to 150-gallon systems for around $200. The Reef Octopus Classic 110-INT is a reliable step below that for 50 to 75-gallon tanks.
Salt Mix and Mixing Supplies
Instant Ocean is the standard for new aquariums. It's consistent, affordable, and available at most pet stores. Reef Crystals by the same manufacturer includes elevated calcium and magnesium for reef tanks. You'll also need a clean container for mixing saltwater (a 30-gallon food-grade trash can works), a powerhead to mix it, and a heater to bring it to temperature before water changes.
RO/DI Water Filter
Tap water contains phosphates, silicates, and chloramines that cause algae blooms and stress sensitive animals. An RO/DI unit (reverse osmosis plus deionization) removes all of these. The BRS 75 GPD four-stage unit is a reliable and affordable starting point at about $100. Buy a TDS meter (inexpensive, under $15) to verify your output water reads 0 TDS before using it.
Refractometer
Salinity needs to stay at 1.025 to 1.026 specific gravity (35 ppt). A refractometer calibrated for seawater and calibrated with NIST-traceable fluid gives accurate readings. The Milwaukee MA887 is the most commonly recommended model at around $30.
Heater
Marine fish do best between 76 and 80 F. Use two heaters rated for the full tank volume rather than one. If a single heater fails in the off position, the second heater maintains temperature. If one fails in the on position, the tank doesn't cook because two smaller heaters can't reach dangerous temperatures as quickly. Cobalt Aquatics Neo-Therm and Eheim Jager are consistent performers.
Circulation Pumps
Fish need at least 5 to 10 times the tank volume in circulation per hour. Corals need 10 to 20 times. Tunze Turbelle and Ecotech MP series are premium options. Jebao RW series wavemakers (RW-4, RW-8, RW-15) offer good value at $30 to $70.
Tier 2: Supplies to Add During the First Six Months
Auto Top-Off System
Evaporation raises salinity as freshwater leaves the tank. An auto top-off (ATO) system detects low water level and refills with fresh RO water automatically. The Tunze Osmolator 3155 and Neptune ATK are reliable options. Even a simple float-valve ATO from Innovative Marine (about $50) beats topping off manually every day.
Testing Supplies
You need accurate test kits for alkalinity, calcium, magnesium, nitrate, phosphate, and pH. Salifert and Nyos kits are the most accurate for the price. Digital Hanna Checkers (HI755 for alkalinity, HI713 for low-range phosphate) give more precise readings than color-matching kits for the two parameters that matter most in reef tanks.
Live Rock
Live rock is your primary biological filter. Porous rock colonized by beneficial bacteria converts ammonia to nitrite to nitrate through the nitrogen cycle. Plan on 1 to 1.5 pounds per gallon. Marco Rocks and Pukani dry rock are pest-free and cost $3 to $5 per pound. Seeded live rock cycles faster but can introduce Aiptasia and pest crabs.
Sump and Filter Socks
A sump (a second tank in the stand below the display) houses your skimmer, return pump, and other equipment out of sight. It also adds water volume. A 20 to 30-gallon sump is appropriate for most 75 to 125-gallon display tanks. Filter socks (200 micron) catch large particulates entering the sump. Replace or rinse them every 2 to 3 days to prevent them from becoming a nitrate source.
Tier 3: Supplies for Established Reef Tanks
Dosing Pumps and Supplements
As corals grow, they consume alkalinity and calcium faster than water changes alone can replenish. The BRS Two-Part dosing system (two peristaltic pump heads, about $60) automates daily additions of alkalinity solution and calcium/magnesium solution. For larger reef systems, a calcium reactor (which uses CO2 to dissolve aragonite media) is more cost-effective long-term.
Lighting for Corals
Soft corals and LPS tolerate moderate lighting. SPS corals require high-intensity, full-spectrum lighting. AI Hydra 32 HD fixtures cover a 24-inch square footprint for mixed reefs. Ecotech Radion XR15 Pro and XR30 Pro are the high-end choice for SPS-focused systems.
Refugium Supplies
A refugium is a separate lit chamber in or alongside the sump that grows macroalgae (usually Chaeto or Caulerpa). Macroalgae absorbs nitrate and phosphate and exports them when you harvest it. A simple clip-on LED grow light (Kessil H80 Tuna Flora, about $90) running on a reverse daylight schedule handles most refugiums effectively.
For a curated breakdown of the top equipment options across all these categories, the Best Aquarium Equipment guide covers the highest-rated products with pricing. The Top Aquarium Equipment roundup is especially useful if you're building a complete system from scratch and want comparative options.
FAQ
What's the minimum budget to set up a basic saltwater tank?
A 30-gallon fish-only tank with a basic hang-on skimmer, simple circulation pump, heater, salt, and test kits runs about $400 to $600 including the tank. An RO/DI unit adds another $100. A sump adds more. Reef setups with quality lighting start at $1,500 for a 75-gallon build with mid-range equipment.
Can I use an old freshwater tank for saltwater?
Yes, as long as it passes a silicone seal inspection. Rinse it thoroughly, inspect every seam, and water test it before filling with saltwater. Any soap residue from cleaning can be toxic to marine life, so clean with white vinegar only.
Do I need a chiller for a saltwater tank?
Most homes maintain temperatures in the acceptable range for marine fish without a chiller. LED lighting runs cooler than metal halide, which reduces heat input. If your tank consistently exceeds 82 F in summer, an aquarium chiller (Aqua Euro, IceProbe for smaller tanks) prevents heat stress. They're not cheap ($200 to $600), so try cooling the room first.
How long does it take to cycle a new saltwater tank?
A tank with dry rock and no bacterial supplement typically takes 4 to 8 weeks to complete the nitrogen cycle. Using live rock and Dr. Tim's One and Only or Fritz Turbo Start 900 can cut this to 2 to 3 weeks. Test ammonia and nitrite every 2 to 3 days. The cycle is complete when both read zero and nitrate is detectable.
Building Your Supply List
Start with water quality: RO/DI unit, salt mix, refractometer, and a protein skimmer. Add filtration: live rock, heater, and circulation pumps. Test your water: get accurate test kits before anything lives in the tank. Then cycle, be patient, and add livestock slowly. The rest of the supply list fills in naturally as your experience and your tank's needs grow over the first year.