[Br14n55reef]

yes 4 hrs will keep your live rock "coraline algae" alive. If you want leave lights off, I let my tank cycle with lights on with these results, 1 Brown algea which is normal
2 Cyano which was gone in 4 days also normal
3 hair algae, which is normal beleave it or not but it goes away and your tank is fully cycled by this stage.
Patience is key in salt water along with weekly small water changes and testing along with algaes, You will always have algae in saltwater so I would go with lights on.
G/L Brian
PS If you have any more questions feel free to ask