We are looking to upgrade our 18 ft Coleman pool. Has done well for us but showing some rust on the top rails. We are looking to stay at 18 ft or jump up to a 21-ft. We are looking for a saltwater capability. We were looking at pool Factory. We are looking at the Aurora all resin, saltwater 8000 and 5000. We want something that's going to last a very long time. We are looking at the Hayward 21in sand filter and 1.5hp 2 speed pump. Also going with their thickest liner the 40 gauge. What do y'all think. Did the resin walls have any downside. We just want something that's going to last and not give us any issues. Or is there any other above ground pool I should look at from a different place. Also is the pump and filter good? And is there a point where the liner is too thick.