I know going dark may work and many people recommend it but I think it is a waste of time. Again, that is my personal opinion. Your algae is growing because something is feeding it. You can turn off the light and get it to die off, but that doesn't deal with the underlying problem of nutrients. Granted, if you can completely eradicate any trace DNA from the algae it will be gone forever, but something else will just take it's place.
If you have nutrients leaching from your rocks or sand, when the algae consumes it all, the algae will die. The more algae you grow in your tank, the faster it will consume nutrients, and the faster it will die off. The problem is that it looks ugly so no one wants to go this route.
This is why people grow Chaeto in their sumps or build algae scrubbers. The idea behind this is to grow the algae where you want it to consume the nutrients instead of in your DT.