I have read through many post and watch all of brs videos on dual membrane. I have 350+tds in my tap so running a dual membrane isn't a great idea. I thought about it and thought of an idea to fix the issue. My rodi came with space saver di housings that I have since upgraded. I thought could I pack one with di resin and run it in between the 2 to membrane. Yes I know the di resin will deplete fast and the membrane would not do anything. But what if I let the di resin go bad and let upto say 200 tds through before changing the resin. Just looking for ideas to double production and lower waste water.