This was also my question. 1 seems to do a good job for a mixed reef. If you are going wall to wall high par SPS, then there is a par fall off in the upper left/ right. I have a 36x30x24 (lxwxd) tank for my next project and am planning on 2 mounted front-back for that.Interesting. I have a 100.3 and was wondering if 2 sky would be needed. Right now I run an orphek Atlantik high over the tank and feel it’s perfect for my tank still after 3 years, but I did wonder about the sky still.
