Pump head question

First of all let me say thanks to all the ppl who responded to this post.
this is my first setup and I got a lot of friendly info. I went ahead and
put the pump at sump lvl with a 6' head but it is still pumping at an
acceptable gph and my tank is working great.
thanks again.
G.

"SalahiAndSon" wrote in message
...
When you see a pump head rateing is this for output length only or both
input and output length combined? Iwaki pumps are rated at a specific gph
at
a 4' head. I have 3.5' from the sump to the pump and 4' on the output side
to my tank. is this considered a 7.5' head or does the head rateing only
apply to the output side? Could someone please explain this or maybe point
me to a site or equation to make it simple. Any advice would be greatly
appreciated.
thanks
G.