I don't think anybody knows for sure if there is a significant benefit to having trace elements in freshwater when they are available in the food. Like Al, I think it is strange that it doesn't increase the TDS. I sometimes use a similar additive called Discus Trace, which has trace elements like iron, selenium, zinc, iodine. But Discus Trace is meant to provide both the trace elements as well as the major minerals calcium and magnesium. It is mostly Ca and Mg, so if you subtracted these and had only trace elements in tiny amounts, probably it would not noticeably increase TDS. Does the continuum list the ingredients?