To follow up on the subject of using RO water for hydroponics...
Most commercially available nutrients for hydroponics are based on the grower using RO water. Variations for hard water, well water, city water, etc. can be found.
I found it is easiest to start with clean water, add back the nutrients and then adjust the pH.
So, I found a food grade water tote on craigslist for about $60. After cleaning and sanitizing it, it was ready to go. But, one of the biggest problems is algae growth in the water system so I painted it black to block the light and then white to make it pretty. I figured the cage would look good in blue, so I painted that too.