This is what I was worried about... but my tap water is so high with crud it’s about 450-550 out of the tap and it leaves white stains in my buckets... really harsh water and it’s tough to grow plants with it but I’ve accomplished it a few times. Lol My plants react so much better to the RO that in my case I think I need to stick it out. All I have on hand is botanicares cal-mag product.. I have concerns with using botanicares formula with GLNs but maybe it will work? Ill prolly be on stand by to purchase GLN’s cal-mag if the need arises. Hopefully it does not though.Going to give up the RO water. MC with my RO water I started at 5.1PH. I was adding 1.5 ml of PH up (soluble potash) 0-0-45. After mixing up the well water batch it leveled out at at 6.5. I can start to see a mag issue starting so I would rather try and drop the RO water before adding more stuff not made by GLN.