I’m not a fan of the scientific rigor of moonshiners, and what you state they say would only be convincing if it was directly compared to something else in the same system, and then would only apply to that specific something else.
This question is very complex. Some trace elements in seawater are almost completely bound by organic matter. Copper is an example. A carbon that bound organics would tend to bind these trace elements.
I’m not convinced that most activated carbon is a substantial directly binding sink for most trace elements.
Oceamo made some measurements. He does not identify the brand used, but it is clear that minerals such as GFO and
Aluminum oxide bind far, far more trace elements.