Soooo guess what I just freakin realized...
A cheap alkaline filter raises pH 1.0-1.5.
PROBLEM! SOLVED!
Every strain I own handled the 4.9 pH water for 2 days, all except one,.. and its a good one (Headband) so I'm real thankful I did a little reading and realized this fix. She got canoe leaves 2 days after I turned off the pH up. It's a mag def, I've dealt with it before with this strain. Soon as I hit it with an Epson salt mist of proper pH'ed water its happy again.
Everyone with this RO low pH issue already has an RO system (obviously) and if you have a strain like me that don't like low pH water, or need to move it up for some other reason, instead of spending money on pH movers (even earth juice) why not spend it on another filter? An Alkaline filter. Doesn't matter if its pre or post all your other filters, just long as its in there it seems to work for me. pH is 6.0 now.
I'm sure the right soil will do the job of buffering, but I kinda wonder why force it into slavery by pouring 4.9 on it everyday.