Starting a marine aquarium is one of the most rewarding hobbies you can take on, but getting the foundation right makes all the difference between a thriving reef and a frustrating experience.
Choosing Your Tank
For beginners, we recommend starting with a tank between 120 and 200 litres. Larger volumes of water are actually more forgiving — they're slower to change temperature, pH, and salinity, giving you more time to catch and correct problems. Avoid anything under 80 litres for your first marine setup.
Look for a tank with a built-in sump or overflow system. A sump gives you space to hide equipment like heaters, protein skimmers, and return pumps, keeping your display tank clean and uncluttered.
Essential Equipment
You'll need:
- Protein skimmer — removes organic waste before it breaks down. This is non-negotiable for marine tanks.
- Heater — marine fish need stable temperatures between 24–26°C. Use a heater rated for your tank volume.
- Powerheads/wavemakers — corals and fish need water movement. Aim for 10–20x your tank volume in turnover per hour.
- Lighting — if you plan to keep corals, invest in quality LED lights with adjustable spectrum. Fish-only tanks can use more basic lighting.
- Test kits — ammonia, nitrite, nitrate, pH, alkalinity, calcium, and magnesium. You'll use these constantly in the first few months.
- Refractometer — for measuring salinity accurately. Don't rely on cheap hydrometers.
- RO/DI water filter — tap water contains phosphates, chloramine, and heavy metals that cause algae and harm livestock.
The Nitrogen Cycle
Before adding any fish, your tank needs to complete the nitrogen cycle. This typically takes 4–6 weeks. Add a source of ammonia (we recommend Dr Tim's ammonia or a raw prawn) and let beneficial bacteria colonise your rock and filter media.
You'll see ammonia spike, then nitrite, then both will drop to zero as nitrate rises. Once ammonia and nitrite read zero consistently, your tank is cycled and ready for livestock.
Your First Livestock
Start slow. Add one or two hardy fish first — clownfish and Royal Dottybacks are excellent choices for beginners. Wait at least two weeks between additions to let your biological filtration adjust to the increased bioload.
Resist the urge to add corals until your tank has been running stably for at least 2–3 months. Your parameters need to be consistent before corals will thrive.
Visit Us
Come into Eastwood Aquarium and chat with our team. We've helped hundreds of customers set up their first marine tanks, and we're happy to walk you through every step of the process.