I'd do 45 if you want that par edge to edge.Hey guys, I'm in the middle of planning a 100G acro tank. Dimensions are 47 x 23 x 19. There is no center brace and I plan to use the mounting arms RB sells. I've seen people using the 35 and 45 lights over four foot tanks. With the mounting bars I am limited to light height so would a 35 be able to have enough spread of 400-500 par in the upper levels from side to side or will a 45 be a safer option?



