Marineland LED Strip Light,18-24" A rocker switch offers 3 modes: white & blue LEDs for daytime, blue LEDs only for lunar effect, and OFF 7800K color temp Adjustable mounting legs offer flexibility in tank sizes and can expand from 18" to 24" 234 lumen output Estimated yearly energy cost: $1.75 (8 hrs per day, 12 cents per kWh)