So basically, RODI is mostly like an insurance and just making sure all the contamination are taken out (if any) before they get into the tank. So, if my understanding is right, RODI is "highly recommended" rather than a "necessity".
Some reefers need to change their perspective
RODI unit is definitely not expensive compared to the cost of this hobby. But what intimidates me is the amount of water wastage. I don't have gardening or anything where I can use the waste water. Plus since its a rented house, wasting water is restricted in the contract. I was actually thinking of starting to by water from stores. Anyone knows where I can find "RODI" instead of just "RO" water?