All of the canisters I have used make lousy mechanical filters. They don't come close to polishing the water. I like the XP3 I have but it doesn't come close to polishing the water no matter what pads I put in it.
To really polish the water you need a DE filter. If you don't want to go the DE route then you need to look at something like a Magnum 350 or NuClear micron cartridge filter. I didn't like my Magnum 350 that much, it isn't energy efficient but it did do a better job at mechanical filtration with the micron cartridge than any of the other canister filter I have used.
I now just use a DE pool filter and my water is always crystal clear.