AquaClear 5000 & how to fligure out flow loss

[oside]

I picked up an Aquaclear 5000 for $30 NIB off the clearance rack yesterday (Good deal?). It is rated at 937-952 GPH.
How do I figure out the loss of flow rate when pumping water up?
Does this powerhead HAVE to be submersed?
Would this work well as a skimmer pump? It came with a venturi/aerator attachment.
It looks like this has been discontinued - are there any parts that I should buy now while I still can? What usually fails on these?

Here are the specs:
(http://www.hagen.com/pdf/AquaClear_PH.pdf)

Once again, TIA !!!

Matt B

[Matt Rogers]

[quote author=oside link=board=Newbie;num=1092353235;start=0#0 date=08/12/04 at 16:27:15]How do I figure out the loss of flow rate when pumping water up?[/quote]

Lots of info out there to find the pump 'head.'
This is a pretty detailed breakdown.

It also has a nugget or two on PVC flow rates which I believe you touched on on another thread.