The top one is the RO
membrane while the first 2 hanging are the RO
filters which has to be replaced more often like every 6 months depending on how bad your water supply is. The last one hanging is the DI
which is the resin you just replaced. If the 240 tds
on the input side of DI
then you definite need to replace both RO
filters and membrane. You should have taken notes on what was the readings when you first installed it.