The lights have a built in timer - i think this is the one aspect of my tank which i don't have a picture of else i'd post it for you, i even have a remote for them but i never use this.
I get a little memory card inside them which i can plug into my laptop and you get a programme pop up in notebook where you can type what you want but it has to be in a specific format for the light unit to understand.
I thought it was rocket science at first but a few trial runs and i figured it out - damn things don't change for the hour time difference in summer though - not that bloody clever are they