tds meter

[fiorano]

i just bought one of those tds meters from wal mart everyone is talking about so i figured i should try out my new toy. so the tap water was 14 ppm, our ro drinking unit was 4. and my ro/di was 2... but im under the impression that it is supposed to be 0. My unit has been running for around 8 months... does anything think i should be changing my filters????? can't you tell if the Di needs replacing because it slowly changes color cause only a half inch on the top and the bottom is a light gold color.