ATO reservoir registering 2-3 tds

[ChadmRoman]

Bought a new ATO reservoir from Crystal Reef Aquatics, sadly soon to close their doors. When I add RODI water it registers 2-3 tds. Traced it all the way back from the RODI reservoir in my garage and it’s only when adding to the new reservoir I get something other than 0.

Is this normal? I did rinse it with vinegar and water when I first got it setup a month ago.

 

[C. Eymann]

Nothing to worry about IMO, RODI is very aggressive in trying to re-establish itself and will "pull" anything it can from any source, even the air itself.