HELP! How to pick the correct pump/filter ??

Hey all, I know it is late in the season for us (well, it is ne fla, so our season is about 9 mo anyway)
I am looking to upgrade my pump/filter set up. I have 1-1/2 inch plumbing already installed, and have no idea what size pump or filter I should go for. I am waiting for the off season in hopes to save a few dollars on a closeout model or something. Open to suggestions there.
My pool is the "wally world" special, 18' x48" metal frame soft wall pool. I was given a 3000gph pump, which seems to move the water well, however, the filter doesn't do the job (vacuming to skimmer, you can see the debris blow right back into the pool, ugh...)
anyway, help would be appreciated, I do plan to upgrade the pool later on, so I would like something that will grow with me and my pool (largest I probably would go is 21-24'.
(ps, pool capacity is about 6800 gal)

The filters that come with Intex pools are not that reliable to begin with, and the cartridge is sub-par as well. You probably just have a dirty filter when vacuuming, so try cleaning it out before you vacuum, until you get a "real" pump. I think your pump might be oversized as well, and I think Intex realized this, as the new ones are around 1500-2000 GPH.

HTH

with the 1500 gph pump, it didnt seem to circulate the water well. This prompted me to hard plumb the intake and return lines. This helped a little. The 3000 gph (at peak efficiency of course) works well to circulate the water, but like the other filter, the cartridge doesn't fit very well, and looks like it blows by a lot of water. When I vacume, I wash the filter before, and after I am done. I try to do this to prevent blow-by.
I just know you get what you pay for, and know a decent set up would give me better results.
Hopefully someone will give me some guidelines to go by when I start looking for a setup.

still looking for some advice to this, there are so many filter and pump set ups out there, it is difficult to pick!
I have decided on a sand filter, and figure I will ad DE to it as needed for polishing. but, where to look, what is a decent price, what is getting ripped off, and, what is too good to be true? (i.e., ebay ?)
any advice???

ANY ONE ? I am looking for advice... am I asking a dumb question ?

Currious if you ever found the answer to your question as I have the same question and am looking for a sand filter system.