Mod Edit: Split from this topic:http://www.troublefreepool.com/pool-...33-t66036.html moderator linen
Look up the gpm ratings of both of the pumps, and the look at the minimum flow rates on the filters your looking at. If you have a filter that's at least 60 gpm minimum u want a pump that flows at least that. 2 inch plumbing would be good for your setup. No matter what you do you will want at least 2 suctions and 2 returns for a pool that big. I actually have 3 of each for my 18x48x4. If you don't, your pump and filter combo will starve for water.
Btw I just got the intex 2650gph sand filter and I love it.