Here's a cheap easy way to make some DIY moonlights that can be easily moved from one tank to another.
Parts needed- 5m (about 15ft) LED blue light strip from ebay ($10) ac/dc 12v/2a power supply also from ebay ($3) Light diffuser panel (lowes about $8 for a big section). If you buy a few power supply units then you can make quite a few moonlights out of the 15ft strip.
Cut the LED strip to the desired length, cut off the end of the power supply, solder the wires to the strip, then cut the diffuser panel to the length of the light strip and zip tie the strip to the diffuser. Done this way you can simply lay the strip on top of any glass lids of any tank it will fit on top of so you can move it from tank to tank.

Here is the one I just made for my 20g tall angel tank
