Setting up a mixed reef is one of the most rewarding projects in the marine aquarium hobby. You get the movement of soft corals, the structure of LPS, and the color of SPS all in one tank. This guide walks you through the key decisions so your mixed reef thrives from day one instead of becoming a chemistry battle zone.

Planning Your Mixed Reef: Tank, Gear & Layout

Before buying corals, decide what kind of mixed reef you want: softie-dominant, LPS-dominant, or SPS-dominant. This choice determines your lighting, flow, and long-term maintenance.

Tank size & equipment basics

While mixed reefs can be done in smaller systems, a tank in the 40–75 gallon range gives you more stability and room for coral separation. Aim for:

  • Reliable protein skimmer for nutrient export and oxygenation.
  • Quality LED or hybrid lighting capable of supporting SPS in the top third of the tank.
  • Two or more wavemakers to create random, indirect flow patterns.
  • Auto top-off (ATO) to keep salinity stable.

For a deeper dive on choosing a system, see our Beginner Reef Tank Setup guide.

Aquascape with coral zones in mind

Think in layers when building your rockwork:

  • Top third: High light, strong flow for SPS colonies.
  • Middle: Moderate light and flow for many LPS species.
  • Bottom & shaded areas: Lower light for soft corals and mushrooms.

Pro tip: Leave more open sand and swim space than you think you need. Corals grow, and fish appreciate room to move.

Managing Coral Compatibility & Water Parameters

The challenge of a mixed reef is keeping very different coral types happy in the same water. Success comes from stable parameters and smart placement.

Target water parameters

  • Salinity: 1.025–1.026 SG
  • Temperature: 77–79°F (25–26°C)
  • Alkalinity: 8–9 dKH
  • Calcium: 420–450 ppm
  • Magnesium: 1300–1400 ppm
  • Nitrate: 5–15 ppm
  • Phosphate: 0.03–0.08 ppm

Mixed reefs usually do best with moderate nutrients. Ultra-low nutrients can starve soft corals and cause SPS to pale, while high nutrients may lead to algae outbreaks. Regular testing and small, consistent water changes are your best tools. If you’re new to dosing, our Reef Tank Water Parameters article is a helpful reference.

Coral placement & aggression

Many corals wage chemical and physical warfare. Plan for:

  • LPS with long sweeper tentacles (e.g., some Euphyllia, Galaxea) placed with generous space.
  • Soft corals like leathers and zoanthids kept downstream of sensitive SPS when possible.
  • Carbon use in a reactor or media bag to help reduce chemical toxins.

Tip: Start new corals lower and shadier than you think, then slowly move them up over 1–2 weeks. Light shock is a common cause of early losses.

Stocking Strategy, Maintenance & Long-Term Success

Introduce livestock gradually to let your biological filter and chemistry adjust. A typical sequence might be:

  • Clean-up crew and hardy fish first.
  • Soft corals and easy LPS once nutrients are stable.
  • More demanding SPS after you’ve proven you can keep alkalinity and nutrients steady.

Daily and weekly habits matter more than expensive gear:

  • Top off with RODI water only.
  • Test alkalinity 2–3 times per week until consumption is predictable.
  • Clean pumps and skimmer regularly to maintain strong flow and export.
  • Feed corals lightly but consistently rather than large, sporadic feedings.

As your mixed reef matures, you’ll learn which corals thrive in your specific conditions. Make slow, thoughtful changes, keep records, and resist the urge to overhaul the system after a single bad day. With patience and a clear plan, a mixed reef can deliver color, motion, and growth that stays stable for years. For more inspiration on choosing your first corals, check out our Easy Corals for Beginners guide.

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