By mentioning blue I assume you want nano-reef capability. Use white LEDs with color temperature around 5100°K and 430nm blue to simulate moonlight for optimal zooxanthellae (symbiodinium) health with timing for each light source to simulate normal solar and lunar cycles.
Please be aware I am not a professor of electronics, I am a hobyist, I want white light during the day, and blue for aprox 3-4 hours in the evening.
Many thanks
mrdiscus
There are waterproof rigid LED light bars designed to operate on 12VDC at this site. White and blue are shown but part numbers for each and specifications for exact color and luminous flux are not obvious.