i use under 15ppm ro. used to use zerowater/"distilled". 40 gallons a wk through a couple of those... g didn't like swimmin in her kitchen. it got ugly. the water store guy... keeps it below 15 and i report his figures so he doesn't have to make the trek. so it's basically... that. um... imma try to premix (sorry to jack ur thread, here)... let it set, overnight n a couple diff containers n see how "homogeneous" the effects remain n solution, over 24... if it holds, steady... i might dumpster dive, c if i still have the old bottle & mix a bit n see. go with our "less is often more", montra, before i exfoliate my junk n eyeballs, again.
sorry, @707finisher . I'm a fan.