I've got a question in relation to chloramines. I know chlorine/chloramine will damage the RO membrane. Most RO systems I see have 1-2 carbon block prefilters placed to remove chlorine. However, I've read that most generic carbon block prefilters do not remove chloramine.

RandallB, in his earlier posts, stated that a DI postfilter is needed if your tapwater contains chloramines. Why is this so? Does this mean that the chloramines will pass through the RO membrane and get removed by the DI resin? They won't destroy your RO membrane the same way chlorine does?

I'm concerned as I want to set up an RO system for my wild heckels (which prefer water with TDS of 40 or so. From the tap mine is about 80, in tank it increases to 120) and my water contains chloramines.