I would personally use distilled/RO water. It is nice to know exactly what is in your water, no guessing. I used to use 350 PPM tap water and I think my plants grow a lot better and easier with the RO water. You will have to use CalMag but I bought a bottle of it about 3 months ago and its not even half gone, you only use 1 tsp per gallon.

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The above post is fictional and should in no way be taken as truth.

If I were to grow cannabis, I would only do so to supply myself and my close friends. Doing this would take myself and my friends out of harms way by knowing the source of our cannabis, as well as take hundreds of thousands of dollars off the black market annually. It would also lower the demand of black market cannabis, and would ultimately help keep cannabis out of the hands of minors.