If it has a DI unit then 0TDS is the only acceptable amount. As it creeps up to about 5ppm over the course of several months it is time to renew it. Keep running it for awhile to see if it clears out all that new product stuff and settles in.

Wanted to add that if the restrictor is not set correctly you coul dbe getting a lot of blow by from the membrane into the DI unit and overwhelming it.