Intex pool pump upgrade

I have a Intex ultra frame 20x48. I am currently using the pump that came with it which is an Intex Krystal Clear 635t 1500 gph with a size A filter(I do have the better filters that can be cleaned and reused). I have been wanting to replace the pump as I don't feel like its getting the circulation the pool needs to keep clean. I have seen it posted you don't want to get too big of a pump and I'm not sure what I can get that will hook up to the pool. Any advice would be appreciated!!

I just installed the Intex 2650 on my pool that is the same size and I am amazed at the difference. This is a sand filter also and seems to clean a lot better than the original pump and filter.