How long to leave the light on???

[2wrestlers]

I have had my 75gal fish only tank for about 3 years now but I hardly ever turn the light on. The only light I have is a 48" 50/50 reef/sun bulb that says it is 6500k trichromatic daylight phosphor and actinic 420 phosphor in the same lamp. My tank is in my bar/pool room in the basement so there is no direct sunlight on it but it is light during the day. I am wondering if the light can be left on all the time. In the tank I have a crushed coral base with about 50lbs. of live rock(about 50lbs more to be added in the next couple of days) and my fish are:
1 maroon clown
1 pecula clown
1 flame angel
2 yellow tail blue damsels
2 green chromis damsels
1 royal gramma
1 yellow tang
along with 20 blue legged hermit crabs
2 brittle starfish
and 1 snowflake eel

 

[salty blues]

I personally would not run lights all the time. The fish probably enjoy a break to rest, and running lights excessively will more than likely contribute to algae problems.