head loss calcu

[fishguyxd]

I have tryed two of them using same numbers and get diff answers
I use 6 ft for length and a mag9 pump as my example no unions or valves yet. I get 7.16 head pressure and flow rate of 635 gph at reefshow site and at reef centrel site i get 7.84 head pres. and 587 gph so I was told i need about 10X tank cir per hr.for good flow so i would need 720 correct for a 72 gal tank could someone tell me if this is correct or what i do need other than more reserchand experience if i use a mag 18 is that to much flow or should i use like a mag 12 or rio 20hf.to get the right numbers