If you use RO or distilled water you NEED CalMag Plus

[bitemybud]

I disagree about the calmag. I've never heard of it and therefore never used it. I have discovered that using r/o water with Advanced Nutrients Sensi Grow/Bloom works out perfectly in a hydro setup and that is all I ever use. I never have to check ph or ec and have had much success. Lucky I guess.

Yes You are.

It is a fact that cal mag is necessary for optimum growth. Ask any commercial or professional grower.

While I am at it. Someone asked about amount to use.

For seedlings; You might add 3ml per gallon. The bottle says to use 5-8ml.
I generally never use 8ml unless late in flower week 4-7, before flush.