My problem with rope lights is they're too bright. I made my moonlighting in my 25g by using 2 blue LEDs, wired in parallel and 2 AA batteries with a switch in between. Gives the 'nightlight' effect nicely, without being very bright. I've had them on there for about 2 months, turned on every night - and they still have the original batteries. LEDs suck down very, very little power. On my 10G breeder/QT, I leave the single LED moonlight on all the time, since the garage can be dark - no windows. I think they're a much better choice for moon lighting if you're handy with DIY stuff.