I love all this info! I had only thought of the positives from the tap water after the stabilization of the PH but you're right, tons of other things in it too or killing off of the good bacteria! I did add that water with the intention of changing it out completely this weekend to fresh RO with new nutes. I may continue to try to use tap just to top off simply because I hate going to the store and filling up my jugs. I think I may invest in some small RO system in the near future. I probably spent at least $50 on water in my last grow.