R.O.
I wouldn't think that a filter change would have any effect on the smell of the water. The pore size on one filter to another should be the same, so its ability to trap anything shouldn't change. I would guess that either your water is getting old or that it need a good shocking. However I may be wrong and one of the more knowledgeable water care people may be able to help. In our pool we notice a musty smell now and then, when I notice it I shock the pool with MPS and all is well
