I am not new to reefing and saltwater tanks. That being said I haven't experienced anything like this before. I put together a small 30g nano tank about three months ago. I purchased a good amount of marine pure that was well cycled from the fish gallery, which resulted in a very fast cycle. After about the first month the tank was cycled and water quality was amazing. About a month later I got a dark green algae bloom almost over night. I did daily 5g water changes and turned down the lights. Now it's just very cloudy and it has been this way for about 3 weeks now. Nitrates, ammonia and phosphates are almost all non existent.