Fortunately, it doesnââ"šÂ¬Ã¢"žÂ¢t need to be pitch-black dark in the tank in order to prevent algae from growing. My 120 is in an interior room of my house and even in the middle the day, without the lights on, the PAR is barely 1 (with lights on the PAR ranges from 1500 just above the water surface to around 200 on the bottom corners of the tank).
As far as the need to take the rock out of the tank to shake it off, or the need to change water, it all depends on how dirty the rock is to begin with.
I started out with pretty clean rock to start, so all I did was blast the rock with a Maxi-Jet once a week and siphon out some heavier debris, which had settled to the bottom of the tank and the sump. I had to add a half-gallon of water a day to replace what my skimmer removed, and about three or four additional gallons a week to replace what was removed during from the debris removal sessions. Otherwise, I only did one water change (about 80%) right at the end of the rock-cooking session. About the only degradation in water quality I could see was cloudiness from a bacterial bloom for about a week.
When the rock cooking was done, I knew everything had worked out ok because after I turned the lights on, I didnââ"šÂ¬Ã¢"žÂ¢t have to clean any algae film off the glass for another three weeks.