whats the difference between RO and RO/DI

[rooksy]

Ok maybe a dumb question, but whats the main difference between RO and RO/DI will both work for tanks? I know RO/DI is better but why and is it worth the expense? Can one unit work for both drinking water and tank water?
Getting Headache so confused, HELP!

 

[option720]

The difference between the two is that RO is just Reverse Osmosis and RO/DI is that plus it de-Ionizes the water. I believe this rids the water of silicates, Phosphates and other junk.
If i remember correctly, RO/DI water taste pretty nasty. But both are great for your tank, is RO/DI worth the exrta cash....It's up to you. I buy my RO water at WinCo for 28 cents a gallon. Hope this Helps.