Starting your first saltwater aquarium is exciting—and a little intimidating. Between tank sizes, filtration options, and lighting choices, it can feel like there’s a lot to get right. The good news: with a bit of planning, your first reef or fish-only system can be stable, beautiful, and beginner-friendly.

Step 1: Choose the Right Tank Size and Style

The size of your first saltwater tank is the most important decision you’ll make. It affects stability, equipment costs, and long-term enjoyment.

How Big Should a Beginner Tank Be?

Very small tanks are tempting, but they swing in salinity and nutrients quickly. For most new hobbyists, a sweet spot is:

• 20–40 gallons for a compact but manageable setup
• 40–75 gallons if you have the space and budget for extra stability

Larger water volume is more forgiving of beginner mistakes, especially with feeding and top-off.

Fish-Only vs. Reef-Ready

Decide early whether you want a fish-only tank or a reef with corals and invertebrates:

• Fish-only: Simpler lighting, more stocking options, lower initial cost.
• Reef-ready: Requires stronger lighting and better water quality, but offers the classic glowing coral look.

If you’re not sure which way to go, start with a fish-only-with-live-rock system and plan equipment that could support corals later. For a deeper dive into planning your livestock, check out our guide on beginner saltwater fish stocking.

Step 2: Essential Equipment for Your First Saltwater Tank

Once you’ve picked a size and style, it’s time to match the right equipment. Focus on reliability over bells and whistles.

Filtration and Water Movement

• Live rock or bio-media for biological filtration.
• Hang-on-back filter or sump to hold mechanical and chemical media.
• Powerheads to create random, gentle flow throughout the tank.

Pro tip: Aim for 10–20x your tank volume in total water movement per hour for a mixed reef, and slightly less for a calm fish-only system.

Lighting and Other Core Gear

• Lighting: For fish-only tanks, modest LED fixtures are fine. For corals, choose a reef-capable LED with adjustable intensity.
• Heater and thermometer: Keep temperature stable between 76–78°F (24–26°C).
• Auto top-off (ATO): Not mandatory, but extremely helpful in keeping salinity stable.
• Test kits and refractometer: Essential for monitoring salinity, ammonia, nitrite, nitrate, and pH.

For help dialing in parameters, see our article on ideal saltwater tank water parameters.

Step 3: Planning Location, Maintenance, and Budget

Where you put your tank and how you plan your routine will determine how easy it is to care for.

Tank Placement

• Avoid direct sunlight and drafty windows.
• Use a sturdy stand rated for the full weight (water, rock, and equipment).
• Leave room behind and under the tank for cables, plumbing, and maintenance.

Time and Budget Reality Check

• Plan for weekly 10–20% water changes.
• Set aside a monthly budget for salt mix, filter media, and test reagents.
• Start with a small, hardy stocking list and add livestock slowly.

When you’re ready to cycle the tank and add your first residents, our step-by-step guide to cycling your first reef tank will walk you through the process.

Choosing your first saltwater tank doesn’t have to be overwhelming. Pick a stable size, invest in reliable core equipment, and give yourself time to learn as the system matures. With thoughtful planning and a steady routine, you’ll be rewarded with a thriving slice of the ocean right in your home.