Perry, thanks for the response and the link. I had forgotten about that thread. Did you use 5V LEDs on your tank? I'm trying to do exactly what you did, but my LEDs don't seem to be working. I figured the problem was that I wasn't providing enough voltage. I thought the headlight circuit was 3.0V. So, when the LED that I soldered into the tank didn't work, I tested the other ones with a couple of AAs. The AAs don't seem to power the other LEDs, either.

Note: I'm testing in a dark room on teeth and $20 bills. No fluorescence. These are LEDs I got: http://www.ebay.com/itm/1-5-10-20-50...:X:RTQ:US:1123

What might I be doing wrong?