RO - TDS

[Aussiemarine]

So I just filled up my RO container ready to swap out the empty one and when I checked the TDS it’s saying 76!! Which is odd because I usually test once a week and the TDS is always 0. So I got a clean cup and filled it up with RO water and tested and it’s indeed 0 straight out of the RODI.

My question is, does this mean my container is contaminated in some way? I have heard that the TDS will rise over time being exposed to the air but this was freshly made with little exposure to outside elements. How do I avoid this sort of issue in the future?

for reference I am using blue food grade 20ltr plastic jerry cans.

 

[lapin]

Maybe a bad test?
Could you have spilled salt in the container?
Funny it would go from 0 one week to 76 the next

 

[RobB'z Reef]

I've noticed a creep over time from my output to long term stored to water. I'm only guessing it may be due to CO2 absorption. But I'm talking about zero output from my rodi unit to less than 10 tds. Again this is just a theory. How new is your storage unit? Some of them can have plenty of impurities due to mfg processes and shipment and storage practices