Ok, so not UV, not needed for growth, only visual appeal/black light fluorescence? Here are some pics of my sad 77 gallon tank a few years ago when I added 2 rows of RGB SMD5050 water proof LED strips to the multi chip build. I recently replaced them with SMD5630 cool white strips since the RGBs were a bit finicky. Fun to play around with, but tended to drift in colour when in the "white" mode which is what I primarily used them for to supplement the 10 watters. They come on 5 meter reels & with the IR remote control pad you can play around with all sorts of colour combos. They can be cut to size, plenty of options for coverage. I used aluminum angle bars to mount them.
Blue, made my modest collection of LPS & montis glow nicely.
Purple, achieved by the IR controller mixing the RGB's intensity.
Red, just for a change up, supposedly good for night viewing of your nocturnal critters.
For < $30, you could probably get a 5 meter reel of blue spectrum waterproof SMD 5050 LEDs, with power supply & possibly a remote or dimmer. Cut to size as many lengths as you need for your tank & lots left over to do up a room with your old black light posters from the '70s. There are clip type patch cables to link the strips together after you cut them, no soldering required.....although I've found the clips to be a little finicky too, so soldering is probably better in the long run.