I’m fully aware and algae needs light but know that zooxanthellae is a photosynthetic algae (not green algae) and anemones have zooxanthellae in their body, which are symbiotic microorganisms that they feed on. Without proper lighting, the anemone will expel the zooxanthellae and turn white. This process is called bleaching and often leads to death. Furthermore, most coral provide the algae with a protected environment and compounds they need for photosynthesis. In return, the algae produce oxygen and help the coral to remove wastes. Most importantly, zooxanthellae supplies the coral with glucose, glycerol, and amino acids, which are the products of photosynthesis. The coral uses these products to make proteins, fats, and carbohydrates, and produce calcium carbonate. The relationship between the algae and coral polyp facilitates a tight recycling of nutrients.
Zooxanthellae is responsible for the unique colors of many corals WHICH REQUIRES LIGHT. WHICH IS WHY MANY CORAL DIE WHEN THERE IS INSUFFICIENT
Run your tank without light and let me know how that works out