1: you have an outbreak of Cyanobacteria. It's either red or green slime. Not quite algae not quite bacteria.Originally Posted by kotlec
2: if you are running an ATS it is not recommended to use a chemical solution to cure Cyanobacteria as it will overload the ATS.
3: to get your SPS to color up more you can increase your carbonate hardness (KH), also known as alkalinity to 14. Just don't keep it over 12 for long as it's assumed it will harm your corals long term.
4: time to solve depends on your system. If you have a strong nutrient export system via ATS, then a month. If ypu have a weak ATS, and you are only doing water changes, then maybe six months as in my brothers case.
5: My bothers ATS is barely functional. He did power water changes weekly without an effect. And finally dosed a chemical to help. It took out 90%. The rest faded over a month.
I have a sand sifting goby to help cycle waste from the sand bed. Dunno if that helped.
Cyanbacteria grows in low flow. It can't stck under high flow and will blow into the water column.
Light is not really a factor as much as flow and nutrient export. I don't recommend turning out your halides as it will flourish even under PCs/t5s.