I have a 30 gal high mixed reef,two years old and was thinking on adding another Red Sea 50 or ,90 as I have a 90 now to help light D.P tank up more. Good idea or not necessary?
These lights have a 24x24 spread. Ideally you would need two lights. However, the 90 has more than enough penetration so it may be a good idea to not run the 90s at max on that size unless they are raised up pretty high. If you hang it high enough you may be able to get a decent spread but you would need a par meter to figure out what height would work best.