That is one way to do it, however, I prifer putting something over the top of the aquarium and shading the light then removing a bit at a time such as light diffuser three layers and remove a layer each week to 10 days, or several layers of sun screen and remove a layer each week. The length of the photo periord is also a way to do it as you are doing. hope something here helps. watch your corals they will tell you when to increase the length of the photo period. Keep us posted.