How to Use the Aquarium Lighting Schedule Calculator
Aquarium lighting directly affects not just photosynthesis in plants and coral, but also how much algae grows in your tank. Enter your tank type (low-light plants, high-light plants, soft coral, SPS hard coral, or fish-only) and the time you turn your lights on, and this calculator returns the recommended daily lighting duration along with when to turn them off.
Low-light planted tanks typically do fine with about 6 hours a day, while CO2-injected high-light plant tanks and soft coral tanks usually run closer to 8 hours. SPS hard coral tanks, which depend heavily on their symbiotic zooxanthellae for photosynthesis, often extend up to 10 hours.
Regardless of tank type, it's safer to start with a shorter lighting period and gradually increase it while watching how your livestock responds, rather than running long hours from day one. Leaving lights on longer than necessary makes unwanted algae blooms more likely, so keeping a consistent on/off schedule at the same time each day helps keep your tank's ecosystem stable.
Frequently Asked Questions
Running lights longer than recommended increases the risk of unwanted algae blooms. Low-light plant tanks in particular should stay close to 6 hours a day.
SPS and other hard corals rely heavily on photosynthesis from their symbiotic zooxanthellae, requiring stronger and longer lighting. Start with shorter periods and increase gradually as the coral adapts.