Why don't you consider a 2ft cube with IOS? I have that set up and I'm using a BM NAC 3.5 in one of my compartments
As for water, you can use Life Distilled water. You can get it at a good price from NTUC, 2x1.5 liters at $0.95, so one carton will be $5.50 and yup! LRs can get from marine life @ hong leong I got mine from henry too!