Where are you taking your reading? If this is after coming out of the DI
resin, you may be due for a resin change. My water supply is 465 tds
, I get 3 tds
coming out of my RO
membrane, and I need to rotate DI
resin cartridges about every 125-150 gallons.
This is where a dual in-line tds
meter comes in very handy..... you hook the first meter between the RO
membrane & DI
canister so you can see the condition of your membrane before the water enters the DI
, then one after the DI
so you know when to change your resin.