TDS Meter Readings

I am making up water and when I test the output water in my Brute Trashcan I get a TDS reading of 6. I test the water in a plastic cup and get 1. Could the Brute Trashcan leach something into the water?

 

I think so. I use the home depot buckets and I test my water coming out of the RODI line and its 0 TDS and 0 phosphates but if I let the water sit in the bucket overnight with a powerhead and a lid on then the water reads .25ppm phosphates. its annoying.

 

You guys test too much

 

It could be the trashcan or it could simply be the air above it. Take a glass container and a straw. Fill the container with RO/DI water straight out of the unit. Do a TDS reading on it. Take the straw, insert it and blow through it for 10 seconds producing bubbles. Do another TDS reading. Some of the air that you blow into it will dissolve into the water and read on the TDS meter.

RO/DI water (and distilled water) is pure water and very unstable. It wants to be at equilibrium with the environment around it. Whether that environment be pure CO2, pure O2, pure nitrogen, or even a Phosphate containing plastic can. It will do its best to absorb/dissolve so that it can come to equilibrium. Thats why blowing in the container of water will alter its TDS reading so quickly. You can do the same TDS test with tap water and it won't be as drastic or as noticeable because of the percentage change in TDS.

In other words, what you are seeing is normal and it doesn't necessarily mean its coming from the container, some of it is coming from the air above the water in the container.