Coral placement and flow decide how your reef grows. Light and water movement shape color, polyp extension, and health. A few small adjustments can prevent big losses.
Map your tank into zones before you glue anything
Start with stable water targets. Keep salinity at 1.025–1.026. Hold temperature at 77–79°F. Aim for alkalinity 8–9 dKH, calcium 420–450 ppm, and magnesium 1300–1400 ppm.
Next, divide the aquascape into light zones. Use PAR if you can. Many soft corals like 50–150 PAR. Most LPS do well at 80–200 PAR. Many SPS prefer 200–350 PAR once adapted.
Plan for growth and shade. A small acropora can triple in a year. Leave 2–4 inches between colonies. Give plating montipora extra room. They can block light fast.
Place corals with sting risk carefully. Euphyllia can reach 6–10 inches at night. Galaxea can reach even farther. Use “sacrificial” rock islands to limit contact. You can read more in reef aquarium aquascaping basics.
- Mark three zones: low, medium, and high light.
- Leave 2–4 inches between different coral types.
- Keep aggressive LPS on the sand or an island.
Dial in flow: enough to clean tissue, not enough to tear it
Good flow keeps detritus off coral and brings food and oxygen. Bad flow causes recession and broken tissue. Watch the coral, not just the pump setting. Polyps should sway, not whip.
Use varied flow patterns. Combine a random mode with a steady baseline. For many mixed reefs, target 20–40x turnover per hour. SPS-dominant tanks often run 40–70x. Start lower and increase weekly.
Avoid direct jets on fleshy LPS. Torch and hammer corals can split or recede. Place them where flow is indirect and alternating. Think “breeze behind a rock,” not “hose in the face.”
Use simple tests to find dead spots. Drop a pinch of frozen food juice upstream. Watch where it settles. Add a small powerhead or redirect a nozzle. Learn the basics in powerhead placement for reef tanks.
- Angle pumps to collide streams for random turbulence.
- Keep sandbed flow gentle to prevent dunes and bare glass.
- Re-check flow after every coral or rock move.
Placement workflow, acclimation, and troubleshooting
Use a “low and slow” placement method. Set new SPS at 50–60% of final PAR. Move them up every 5–7 days. Reduce light intensity by 10–20% if you see paling.
Secure frags with stability in mind. Use gel glue for small plugs. Use epoxy plus glue for heavy pieces. A wobbling frag gets tissue damage. That damage invites algae and infection.
Match coral type to location using real examples. Put zoanthids on lower rocks at 80–120 PAR. Place a candy cane on sand at 60–120 PAR with gentle sway. Put acropora high at 250–350 PAR with strong, shifting flow.
Common mistakes show up fast. Brown SPS often means low light or high nutrients. Bleached tips can mean sudden PAR jumps. Receding LPS can mean direct flow or low alkalinity. Check alkalinity daily for a week after changes. For more stability tips, see reef tank parameter stability.
- If tissue peels on one side, redirect the nearest pump.
- If detritus collects, add cross-flow near the bottom third.
- If corals stay closed, check salinity and temperature first.
Coral placement is a process, not a one-time job. Start with zones, then tune flow by watching coral response. Make small changes and wait a week. Your reef will reward patience with growth and color.
Sources: Borneman, E. “Aquarium Corals”; Delbeek & Sprung, “The Reef Aquarium” Vol. 1–3; Julian Sprung, “Corals: A Quick Reference Guide”
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