scfh/lph

yup, sea level atmospheric psi is 14.7 for every 1k' you loose 3% @ 6k' atmospheric psi is 12.24 which is a 16.73% loss. your sicce250 max is 50 scfh at sea level now your max is 41.6 scfh @ 6k' which means on a heavy bio load that skimmers max is a 150 gallon tank.

this is just taking into effect psi, there are other elements that are involved

check out the rma-8-ssv (range 10-100 SCFH) or the rma-89-ssv (range 15-150 SCFH) both for $35.5 to find out what your skimmer is doing
Dwyer Instruments - Series RM (RMA/RMB/RMC)

 

ive been running comparisons on different manufacturers and it seems the industry bases the loads like this:

units in air intake / total system volume

light: 10-15 scfh/100 gal
med: 15-20 scfh/100 gal
heavy: 20-25 scfh/100 gal

i have yet to find out how the industry arrived at these numbers, more to follow.

 

So why would the XP2000 pull 50scfh but be rated for a 180 gal tank whereas the ATB 840 which is nearly identical pull 20-24.5scfh but is rated for a 250gal tank?

 

exactly my point for this thread. which leads us back my original question

 

Well.. it's really quite simple. At seal level standard temperture of 15 C.. just take your scfh/lps ratio to hyborbolic nanomunchins X sech(x) = 1/cosh(x) = 2/( e x + e -x ) take the square root of that and divide by df / dr = df / dx * dx / DR + df / dy * dy / DR
and that's about it.
Just kiddin way over my head.

 

Thanks for the conversion (scfh to lpm multiply by .47195).