Aquarium Light Calculator
Aquarium Lighting
Calculate the lighting needs for your aquarium
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Formula
Wattage = Tank Volume (gal) x Watts per Gallon (varies by light type and purpose) | Light Length = Tank Length x 0.85
Frequently Asked Questions
How much light does a planted aquarium need?
Low-light plants need about 20-40 PAR at the substrate (1 watt LED per gallon). Medium plants need 40-80 PAR (1.5W/gal), and high-light plants need 80-120+ PAR (2.5W/gal). PAR measures actual plant-usable light and is more accurate than watts alone.
How long should aquarium lights be on?
Fish-only tanks: 6-8 hours. Planted tanks: 8-10 hours. Reef tanks: 10-12 hours with gradual ramp-up and ramp-down. Too much light causes algae problems, while too little prevents plant growth. Use a timer for consistency.
What color temperature is best for aquariums?
Freshwater planted tanks do best with 6500-7000K (daylight) spectrum. Fish-only freshwater tanks can use any color for aesthetics. Saltwater reef tanks need 10,000-20,000K with actinic blue (420-460nm) supplementation for coral growth.
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