I want to build a freshwater (not using epsom salt) system, myself. Similarly, I also want to know about the correct water pump to use.
The other day while surfing the internet on information and resources I came across the following websites that may be helpful (I'm not sure yet; haven't had a chance to really read it all:
http://www.aquariumguys.com/waterpumps1.html Here is a large selection of pumps - Not sure whether there are any on this page that are suitable for warm salty water.
http://www.haywardnet.com/pdfs/Pump_filter_sizing.pdf
Concerning how to choose a pump/filter, I found the precedinging article (PDF format)
Maybe those will be of assistance. I'll be watching this thread also because I'd like to see what others (who know what they are doing) have to say.