TDS=Total disolved solids. The number you watch to know when to change RO membranes. Seems like your PH should be lower, hence the reason I asked for your numbers, thinking maybe the membrane's shot. Not sure how you can maintain a RO system without monitoring this number.... Regardless.....
I keep Marbles, quite a few. Have battled lots of dents (usually WC) have experienced Prazi doing more good then harm, I've seen it increase appetite more then decrease. I've even had good luck with injecting it right into night crawlers. Obviously IF people are recommending using it at 2.5x the regular dose and others agree, I think most of us using it agree, it's pretty safe.