There you go, that's exactly what I was thinking of.
I just had a little test of a single LED just stuffed into the end of the power adapter(Which I managed to find in the bermuda triangle behind my computer desk) and they're brighter than I expected. I'm not sure on the exact amount of light to aim for, but 2 per foot looks like it would be HEAPS, even 1 per foot should be fine. 1 per 2 feet looks like it'd be at least enough to see in the tank with all the lights and the room lights turned off. Looks very nice and the ripples of light, awesome! hahaha. That's running on the 3 volt setting which puts out 4 v and goes down to about 3.5 with the load of the LED. On the 4.5V setting it's kinda odd, it's putting out 5.5ish and the LED gets a much greener tinge. It'd probably burn out really quick like that.