RODI TDS Readings

[Niven]

I just used my RODI from bulk reef supply for the first time a few days ago. My incoming water only registers around 20-25 ppm. That seems impossible......right?

 

[griss]

That seems really low (maybe a blessing) to me. Mine comes in over 100, then after the membrane ranges 6-15, then zero after 3-stage DI.