I have set up a 20 gallon tank for a refugium I am letting all the silicone cure. What are the minimum light needs to grow the correct algaes. Also any ideas on what I should put in there sand algae etc. new to refuges. I figure I had the 20 gallon already and just the extra water volume could not hurt. But little idea how to make it even better. I plan on lighting opposite the tank lights for a easier to manage temp . Thank you for any help