TDS help

So I have had my reef tank running for one year but today is the first day I have ever had a TDS meter. I always used a RO/DI system but was never sure of the readings before and after.



So my TDS reading before the system is 176 and after the system it was 2. I know it is suppose to be zero but I also had the RO/DI system running for a year with the same filters. I also got new filters today too. The question I have is is 2 too high and should I switch the filters now or is 2 fine and wait for it to get a little higher?





Thanks a lot you guys!