Hi! Long time no post. In a nutshell, for 2 years i was skipping the di phase due to amazingly high CO2 levels in my water that ate all my resin. Well, my tank did not do so well, and over the summer it accelerated and all my SPS and most of my LPS died. And I was lazy testing my water, assuming all along that my water was at 5-6ppm. Well, I was pumping 48ppm into the tank! The RO membrane somehow had failed. After 6 years I stupidly crashed my tank, and spent the next six months not caring. The fish and inverts are fine, but my once beautiful reef is barren. So Ive decided to fix it. Bought a brand new spectrapure 90 gpm unit, replumbed it so there is one more carbon block and a seperate DI. I purchased a booster pump. I made a degassing tower. I bought a handheld TDS meter, a ph probe and a CO2 test kit. All in all I threw over $300 into this project. I fired it up yesterday and let it run. I tested the effluent this morning for CO2. Free CO2 after RO = 76 Free CO2 after Degass= 7 Obviously I have achieved a stunning reduction! But I cannot find citations for normal/average/optimal, so i don't know if I have further to go or 7 is good. Does anyone know these numbers?