Dont even bother for mj. If you can all squeeze it into your budget get RO water and cal mag by botanicare.
We are not growing some cheap crop of tomatoes or backyard herb. This is the escalade of gardening endeavors.
It is funny they call it cannabis manufacture.
This is a primo endeavor, we spend all this money and time on good nutes and bacteria and fungi cultivation. Not to mention the time.
Not to mention the dirt. It is not exactly dirt, but even empty it is "super soil" unto itself. Christ I want to be buried in fox farms.
Are plants are what they take in to a point, not just killer genetics.
Mostly it is genetics.
Still there is no reason not to give the best water too, especially to think what it might kill in organics soil.
I organic soil we count on all the little creatures that bad water might kill to feed and nurture our plants.
By nurture I mean fungi can increae our rootmass to a big X amount of times healthily and without over ferting feed banquets while bacteria break down the NPK and feed it to the plant on the plants orders, according to the signals the plant sends out with carbohydrates. Cool story there. . .
Not to mention all the crap chemicals in the water besides chlorine. Weird shit.
I have learnied this a hard way a few times, well quite a few times.
Ro water is cheap.
Not to preach but I was of the wrong mindset once, dicking around with cheap dirt that came with other shit, like weeds and well why not go out for my meds, it pays off!