since silicate is some of the 1st crap to make it past the resins, i will be using that reading to determine when to change..even if my tds is 1,, i have heard it can begin passing as soon as 100g. my source TDS from the well is only 190 and the RO is taking it down to 20, still not bad.
i get diatoms that i need to eradicate soon. heck,,i may even run double DI canisters.