I've used different moonlights on my tanks. As stated, they are really just for night viewing and mine go out after an hour or so.
On one tank I had 3 lighting systems. A dawn and dusk light, the main lighting and a moonlight. The dawn and dusk light was low wattage and provided a transition from darkness to bright light and back again.
For moonlights lights I have used a 15 watt exit sign bulb, a dim IKEA cabinet accent light, kids nightlights and LED. They all give a different hue.
For a cheap LED set up how about buying a string of blue LED Christmas lights? Probably some electrically minded poster could explain how to shorten the string to just a few bulbs.
I'll try to post a shot of my lights tonight.
The LED's didn't even register but here's my IKEA solution
________
roor bong pictures