Cut back on the light power.. or change the color of lights. Lights in the high in reds cause algae to grow... no red night light, either. Too much light in the normal florescent ranges will grow algae to quickly. Your lights should be strong towards the blues. What lighting do you have?
What are you feeding, how much and how often? Tank inhabitants?Tank info (filtration and size) Lighting schedule? How old are your bulbs? Do you run a fuge? There are excess nutrients in your system causing the algae to grow. Answering those questions can help us solve what can be causing the excess nutrients.
Lighton from 1-9. Aquaclear 110 hob filter. Reef octopus bh 1000 hob protein skimmer. No sump. 2 clowns and 2 demsils 1 turbo snail and some othe small ones.
You are running a HOB filter? You have live rock.. nix that filter IMO.. it may be your problem. If not the problem it is absolutely a portion of it. If you want to keep the filter box for water movement try adding live rock rubble in it and ditch the filter medium. Filters commonly are a root to nitrogen compound problems.