I tried to re-learn my soldering skills today, by making the current limiting resistor board. This is definitely a physical skill that needs practice to make it work well, but I think I managed to get all of the resistors soldered in without shorting out any of them.
I have decided to just mount this inside the light fixture against one wall. But, I'm still thinking about how to avoid droplets of moisture from condensation from shorting out the resistors. Some kind of coating seems like the best idea - silicone?
I will have two DC voltage power cables coming in to the light, one 48 volt for the LEDs and one 12 volt for the fans. Managing that neatly was a challenge. But, I found this device in the RadioShack website, so I will use it.
Half will be mounted at the back of the fixture as a socket, and the other half will be the power plug carrying the two voltages from the power converters. These, of course will be spliced to wires from the power converters, and to a 6 foot or so 4 wire cable leading up from under the tank to the fixture.