CalMag+ in Coco? Do I need it?

[Weezard]

I've read some where that if you have hard water you can add some to RO and distilled water to get some elements in there....

Is that true?
Doc Oc
imp:

Yes, as far as I know.
And I did some testing of R/O vs distilled vs tap.
I'm happy to say, the tap water won.
Saves me a bundle.

Disclaimer:
Your milage, can, and probably will, vary.

Aloha,
Weezard