Hi MR members.I have a fish only tank. I first started with a $100 cheap set up it was 30 gallons with about 30 lbs of lfe rocks,sand aqua clear 50,heater and a skimmer,added a few mollys to cycle the tank and a regular strip light.From there i have upgraded step by step. now i have 75 gallon with 100lbs of life rock a pro clear 125 wet dry,Berlin skimmer. just bought a current nova exteme 4x54 from a fellow MR member.i want to add some coral little by little by i dont have a ro/di system so I need some help on where to get one,how does it work and how to set it up i try the web but the infor is not clear. Any advice would be helpful,thanks