Carbonates, Electro-Right, RO-Right, etc.

>That would be my opinion.  A little calcium carbonate to provide
>some pH stability and a little carbonate hardness for plants is the
>only thing I can think of that really makes sense to add back to
>RO/DI water.

>Nathan H

Isn't the calcium carbonate more for the plants, and the carbonate hardness
more for the pH stability?  The comments above say the opposite.  Please help
me understand this.  I appreciate your help.