Ok. I’m running a 220 6’ long mixed reef. Right now I have one mp40 on each end about 3” below the surface and one on the back way halfway down in the middle. My first question is what does back mode actually do. I see the turquoise light but the controller looks like It never changes speed as opposed to the pumps on the ends in master slave antisync mode the white lights show the speeds ramping up and down. Does that mean in back mode the pump is just always in constant mode while in reef crest or other non smart modes? I saw a diagram someplace that shows back mode working in the NUtrient transport and tidal swell smart modes. What does the back setting do in reef crest, lagoon, short pulse, and gyre? Next I tried using your flow calculator but it seems to recommend much less flow than there standard 50x turnover rate. Why is that?