heres an example. lets say you have a 10g tank (for easy numbers). now lets say you are aiming for 40x turnover. that would put you at 400 gph
. because of the size of tank, you opt to use a return pump rated at 400 gph
(tank has a sump below for this example)
and you only run 1 standard return nozzle. this would blow substrate ALL over the place, destroy prob every coral, and more than likely knock rocks over. now if you took that same setup, split the return line into 2 (one for each side of the tank) than put wideflow nozzles on each side, youd have a wider distributaion of the 400gph across the entire tank, not just one entry point. corals would be happy, water would be contained, and rocks would be stable.