I agree. South Africa cool. Guess we won't be telling you to go to you local home depot there.
Yes activated carbon does remove trace elements along with the bad stuff. As does most other filtering systems including plant life.
The good stuff like calcium and other trace elements should be returned to the system through the various means. The most obvious is substraits like aragonite and curshed coral which buffer calcium, magnesium and others.
I hope you are not adding trace elements without first testing for those elements. I very well could be that a particular trace element is already too high and either the doseing is not needed or is actually degrading the system.
Again south Africa cool. and welcome