Thanx! I believe I am going to be mixing the RO w/ Tap--which for me is: Ph 8.2, Kh ~14-15, Gh ~17-18. So, from what I understand a 3RO:1T should give me about Kh 4-(3.75) and Gh 4.5 correct? Ph right now is unknown to me, so I'll just have to wait until I actually start mixing.

At a low Ph (~6) and a Kh of 3-4---what is my mark for Gh--(for the plants)?

TIA