I am looking for a filter for my new 15' - 4 ' intex pool. I can get a Intex cartridge B type 2500 GPH for $90.00, an Intex 1600 GPH sand filter for $140.00, or an Intex 2650 Sand filter for $200.00. I know everyone will automatically say the sand filter is better but why. Assuming the pump is the same why would a sand filter of the same GPH be so much better than a cartridge filter. Just because people switched from an undersized cartridge like a Intex 600 GPH to a 2650 GPH sand filter doesn't mean a 2650 cartridge filter wouldn't do the same thing. The cartridge filter is about half the price. Also are there other brands of small filters that are any good?