Setting up a saltwater tank requires more equipment than a freshwater setup, but the list is more manageable than most beginners expect. The core supplies you need for a saltwater aquarium are: a tank, a protein skimmer, a return pump or quality HOB filter, live rock or ceramic biological media, salt mix, a refractometer, a heater, quality lighting (more important in reef tanks), water conditioner, and a test kit covering ammonia, nitrite, nitrate, and pH at minimum. For reef tanks add an alkalinity, calcium, and magnesium test kit.
This guide breaks down each supply category with specific product recommendations, explains what's mandatory versus optional, and helps you build a realistic budget for either a fish-only-with-live-rock (FOWLR) system or a reef tank.
Tank and Stand
Saltwater tanks benefit from glass over acrylic for most home setups. Glass resists scratching from coralline algae cleaning far better than acrylic and doesn't yellow with age. Standard glass tanks from Aqueon or Marineland work fine for FOWLR setups. For reef tanks, ADA, UNS, or Red Sea rimless tanks provide better clarity and cleaner aesthetics.
The most popular starter saltwater tank size is 40 to 75 gallons. Smaller tanks (under 30 gallons) are harder to keep stable because water chemistry parameters shift faster in lower water volumes. A 40-gallon breeder or 55-gallon standard tank gives you enough volume to maintain stability while keeping costs manageable.
With or Without a Sump
A sump is a secondary tank underneath the main display, connected by overflow drains and a return pump. Sumps house equipment (protein skimmer, heater, reactor) out of sight and increase total water volume. They're not strictly required but are standard in tanks over 55 gallons and strongly recommended for reef setups.
If you're starting without a sump, an HOB protein skimmer and hang-on-back filter can handle a FOWLR setup in tanks up to 75 gallons.
Salt Mix and Salinity Measurement
You'll use salt mix every time you do a water change. There's no getting around this ongoing cost, so buying salt in bulk makes sense from the start.
Salt Mix Options
Instant Ocean Natural Sea Salt is the baseline choice for FOWLR tanks and fish-only systems. It's been a hobby standard for decades, mixes consistently, and costs around $30 for a 200-gallon bucket. The salinity and basic chemistry are reliable.
Reef Crystals (also from Instant Ocean) is the next step up, with elevated calcium, magnesium, and trace elements designed to support coral growth. It costs $35 to $45 per 200-gallon bucket. For a reef tank, the extra cost per gallon is minimal compared to the coral supplementation it offsets.
Red Sea Coral Pro Salt is the premium choice for SPS and LPS coral-heavy tanks. It mixes to higher alkalinity levels that support rapid coral calcification. At $50 to $70 per 200-gallon bucket, it's more expensive but reduces the need for two-part dosing in many setups.
Measuring Salinity
A refractometer is mandatory for accurate salinity measurement. Digital or optical refractometers accurate to 0.001 specific gravity cost $20 to $40 on Amazon. The Milwaukee MA887 and the Vee Gee STX-3 are both reliable in the hobby.
Target specific gravity of 1.025 to 1.026 for most reef setups. FOWLR tanks can run slightly lower at 1.023 to 1.025.
Avoid plastic swing-arm hydrometers. They're inaccurate by up to 0.002 specific gravity and can give false readings that cause salinity-related fish deaths.
Protein Skimmer
A protein skimmer is the most important filtration tool in a saltwater aquarium. It removes dissolved organic compounds (DOCs) before they break down into ammonia, reducing the overall bioload on biological filtration. In a reef tank, protein skimming is the primary method of nutrient export alongside water changes.
FOWLR Skimmer Choices
The Reef Octopus Classic 150-INT handles up to 150 gallons and costs $180 to $220. For tanks under 100 gallons with moderate fish bioload, the Bubble Magus Curve 5 at $130 to $160 is a popular budget option that performs well.
Reef Tank Skimmer Choices
For reef tanks, invest in a quality skimmer. The Reef Octopus Elite 150SSS at $250 to $350 and the Red Sea RSK-300 at $350 to $450 are the two most recommended models in the 100 to 200-gallon reef range. Both produce consistent, dark skimmate and require minimal adjustment once dialed in.
Our guide to the Best Aquarium Equipment covers protein skimmers in detail alongside other core saltwater hardware.
Biological Filtration: Live Rock and Media
Saltwater tanks depend on biological filtration to process ammonia and nitrite. Live rock (rock colonized by bacteria, coralline algae, and microfauna) provides an enormous surface area for these bacteria to inhabit.
Live Rock
Aquacultured live rock from the US is the cleanest option. It arrives colonized but without the pest hitchhikers (mantis shrimp, aiptasia anemones, unwanted crabs) common in wild-collected rock. CaribSea LifeRock is a popular artificial alternative that arrives without hitchhikers and colonizes quickly. It costs around $3 to $5 per pound, and most tanks need 1 to 1.5 pounds of rock per gallon for adequate biological filtration.
Ceramic Biological Media
For sump-based setups, Seachem Matrix is a porous ceramic media that provides exceptional surface area for beneficial bacteria. A 4-liter bag handles up to 800 gallons of biological filtration capacity and costs $25 to $35. Running Matrix in the sump bio section along with live rock in the display provides redundant biological filtration.
Lighting for Saltwater Tanks
Lighting requirements vary significantly based on what you're keeping.
FOWLR Tanks
Fish and live rock don't have high lighting requirements. Any LED fixture that illuminates the tank clearly for viewing is sufficient. The Nicrew SaltWater LED at $30 to $50 or the Fluval Marine and Reef 3.0 at $80 to $120 cover FOWLR needs well, providing a daylight plus blue channel combination that makes fish colors pop.
Reef Tanks
Coral lighting is where costs increase substantially. Soft corals and LPS corals like hammer coral, torch coral, and elegance coral do well under mid-range lighting. The AI Prime 16HD ($150 to $200 per fixture) handles a 24x24-inch footprint and is programmable through the myAI app.
SPS corals (Acropora, Montipora, Pocillopora) require high PAR (photosynthetically active radiation) levels, typically 200 to 400 PAR at the coral placement. The AI Hydra 32HD ($350 to $400) and the Radion XR30 Gen 6 ($650 to $750) are the high-end choices for SPS-dominant reef systems.
Circulation and Flow
Corals require strong, random, multi-directional flow to remove waste from their tissue surface and deliver nutrients. Powerheads or wavemakers inside the display create this circulation.
The Tunze Turbelle Nanostream 6095 generates up to 2,500 GPH in a compact form factor and costs $90 to $110. The Jebao SLW series offers comparable flow at $30 to $50 per unit and is a popular budget choice.
For a 55-gallon reef tank, two opposing powerheads creating flow across the tank prevents dead spots and replicates natural ocean current patterns. Target 50 to 100 times total water volume per hour in flow rate across the whole system for a reef tank.
Water Treatment and Testing
RO/DI Water
Saltwater tanks require RODI (reverse osmosis, deionization) water for mixing salt and for top-off. Tap water contains nitrates, phosphates, silicates, and trace metals that accumulate in a closed marine system and cause chronic algae and coral health problems. A home RODI unit like the BRS 4-Stage system costs $150 to $200 and produces clean water on demand. Alternatively, many fish stores sell RODI water for $0.25 to $0.50 per gallon.
Water Conditioner
For the small amount of dechlorination sometimes needed for fresh top-off water, Seachem Prime works fine at standard dosing. But the primary solution for saltwater systems is using RODI water that doesn't contain chlorine at all.
Test Kits
The API Saltwater Master Test Kit covers ammonia, nitrite, nitrate, and pH for around $25 to $30. For reef tanks, add the Salifert Combo Pack (alkalinity, calcium, magnesium) at $25 to $40 for the three kits. Testing alkalinity twice weekly is the most important routine parameter check for keeping SPS corals healthy.
Our Top Aquarium Equipment roundup includes testing equipment comparisons and recommendations for both FOWLR and reef setups.
Maintenance Supplies
Refugium Macroalgae
Growing chaeto (Chaetomorpha) or caulerpa in a sump refugium exports nutrients naturally. Chaeto absorbs nitrate and phosphate as it grows. Harvest half the mass monthly and discard it. This is one of the most effective long-term nutrient control methods in a reef system and costs only the price of a refugium light (the Innovative Marine Refugium Primer at $50 to $80 covers a standard sump section effectively).
Water Change Equipment
A 5-gallon bucket dedicated to marine use, a powerhead or small pump for mixing salt, and a submersible thermometer make water changes straightforward. Pre-mix your salt at least 24 hours in advance, confirming salinity and temperature match the tank before adding it.
Budget Estimates
FOWLR Setup (55-gallon): Tank $120, stand $80, HOB protein skimmer $150, quality HOB filter $50, heater $35, refractometer $30, salt mix (initial 150 gallons) $25, live rock $150 to $200, basic LED $60, test kits $35. Total before fish: approximately $735 to $785.
Reef Tank (40-gallon): Tank $100 to $200 (rimless), sump $80 to $150, protein skimmer $200 to $250, return pump $80 to $120, reef LED $150 to $200, powerheads $80 to $120, refractometer $35, RODI unit $150, salt $35, live rock $100, test kits $60. Total before livestock: $1,070 to $1,420.
FAQ
What's the difference between FOWLR and a reef tank for supplies? FOWLR (fish-only with live rock) needs simpler lighting, can use looser water parameter targets, and doesn't require calcium, alkalinity, or magnesium supplementation. Reef tanks add the cost and complexity of high-PAR lighting, more precise water chemistry monitoring, and often two-part dosing or a calcium reactor to maintain calcium and alkalinity for coral calcification.
Is live sand necessary for a saltwater tank? Not strictly. Bare-bottom tanks are easier to clean and preferred by some reef keepers because detritus doesn't accumulate in sand. If you use sand, CaribSea Arag-Alive and Nature's Ocean Bio-Activ Live Sand arrive pre-colonized and establish faster than dry sand. 1 to 2 inches of fine sand is sufficient for most purposes. Deep sand beds (4+ inches) create natural denitrification but require specific management to remain effective.
How long does a saltwater tank take to cycle before adding fish? 4 to 8 weeks for a traditional fishless cycle using ammonia. With live rock from an established tank and bacterial supplements, some setups stabilize in 2 to 4 weeks. Test ammonia and nitrite daily during cycling and only add fish when both read zero and nitrate begins to appear.
Do I need an RODI unit or can I use tap water? For FOWLR tanks, aged tap water with a good dechlorinator may be acceptable in the short term if your municipal water has low phosphate and nitrate. Long term, silicates and phosphates in tap water cause persistent algae problems. For reef tanks, RODI water is essentially mandatory, the accumulation of contaminants over months causes coral health decline that's hard to diagnose and reverse.
Getting Started
The single most important decision is whether you're building a FOWLR system or a reef tank, since that determines your lighting and water chemistry requirements. FOWLR is significantly less expensive and more forgiving. Start there if you're new to saltwater, spend 6 to 12 months learning the system, then upgrade to a reef tank with a much stronger foundation of experience. The livestock and supplies will perform better for it.