The problem, as I have found, is that LEDs designed for aquariums don't give a K rating
The one I went for comes in two colours for freshwater - bright white (which is white) and colourplus which is pink and is designed to "make the reds and blues in the fish stand out" (quote from the shop! They had one on a goldfish tank and the fish were bright bright orange under it). I've read that Arcadia tubes are faintly pink, though I've not seen one in use.
The shop also warned about those LED strips that use adhesive pads to fix them in place - they come unstuck. If you go for LEDs rather than replace the ballast and get fluorescents, get those that can fit into the light sockets or those that use circular clips which go round the tube and screw into the lid, assuming your lid allows for that.
And based on my experience with the little 6 inch LED don't put them underwater, even if they are supposed to be submersible (mine leaked).
I know Steve says to get non-aquarium LEDs as they are a lot cheaper (and do have a K rating) but the problems is finding those that don't use the fluorescent ballast as the power supply - you can't do that as yours is dead.
Any links Steve?