New tanks generally go through this diatom bloom for two reason, nitrogen cycle and excess silicates in the aquarium.
Both of which are best served waiting for the tank to fully establish itself before adding livestock. The nitrogen cycle is revolving and systematic to bacteria levels, stocking, feeding and live rock.
Silicates, which is my guess to what your dealing with is unfortunately a let it play out situation. Turning off your lights or even cutting back is not going to change a thing for removing silicates in the system. You'll just be putting off or extending your silicate reduction time. I would also advise against a clean up crew specific to this problem. All snails and crabs are going to do is eat the diatoms and poop out the same silicates that is causing the algae and as such continuing your problem.
Simply put, wait it out while practicing good husbandry along the way.