You shouldn't have any algae during your cycle, unless you're running your lights...... If you are, shut them off. If you're not, then you have a bright light source close to the tank that you need to mask off. There are so many excess nutrients in the tank during the cycle that if algae gets a foothold now it can quickly become a problem before you even get started.
Algae needs light to grow..... an ounce of prevention now will save a pound of problems later.
Wanna calculate the cost of that new reef tank?? Take your worst nightmare, double it, and you're halfway there.