Hi and welcome to the forum!

Im sure other people who know more about lights will reply soon. Ill cover what i do know. Just to wash used fish tank is not enough. Myself i would never use old fish tank for frogs, while not so common M. Marinum can do nasty things to you and your frogs, it is very resistant to everything too.

You can use undiluted bleach for tank, rinse very well and after use 70% alcohol to cover generously every inch of the tank, rinse very well after again. After that You can consider it disinfected and hope m marinum wasn't ever there, because even after these measures there is no guarantee.