So I am trying to decide if I want to add a second mp40 to my 120 mixed reef tank. So durning my research I’ve come across this calculator from echo tech but am having a hard time reading and understanding what it actually means and is trying to interpret. I entered my tank Dimensions and then was given option to choose between mp40 and mp60 and how many of each. So I took screen shots of 1 mp40 graph and graph with 2 mp40 to post here below. My question is looking at these 2 pictures what am I looking at ? Obviously with 1 mp40 graph is in middle of box then when I choose a second it lowers where the lines run thru the graph to bottom of it. Does this mean 2 mp40 are not recommended In my tank because with 1 choose lines are in middle. Please can someone explain to me what we are looking at and what this means. Thanks for any clarification.