How long should I run my reef lights after adding new coral?
Quick Answer
Start new coral at a shorter photoperiod (about 6–8 hours) and increase slowly over 1–2 weeks. This reduces light shock and helps coral adapt safely.
When you add new coral, avoid blasting it with a full 10–12 hour light schedule on day one. Most corals handle acclimation better if you start with a shorter photoperiod and ramp up gradually.
Safe beginner lighting ramp
- Days 1-3: 6 hours at reduced intensity
- Days 4-7: 7 hours
- Week 2: 8 hours
- Then: Increase toward your normal target (usually 8-10 hours total photoperiod)
If your lights are programmable, reduce both intensity and duration initially. If they are manual, raise the fixture slightly or use a screen mesh layer to diffuse output while acclimating.
Signs your coral needs less light
- Bleaching or paling color
- Tissue recession
- Closed polyps for multiple days
If you notice stress, pause increases and hold your current light level for several more days before adjusting again.
Other factors that matter
Lighting is only one part of acclimation. Keep salinity stable, avoid large alkalinity swings, and maintain gentle-to-moderate flow for most beginner corals. Use the ReefBay app to log parameter changes while your new coral settles in.
When in doubt, go slower. A gradual ramp is almost always safer than aggressive lighting changes.
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