I think you managed to pick up quite a lot in 18 months ^^
although we're all still learning!
All active carbon does is take up chemicals
So yes, meds will be filtered. Also, carbon tends to release minute quantities of phosphate...
I looked up the standard filling of the Eheim ecco2;
I'd say load the two the same way.
from in to out:
The Eheim MECH pro (the plastic tubes), maybe with some very loose extra filterwool first to trap larger particles
Biomedia (substrate pro) one or two trays even (could also be fine spunge)
chemical, if you want (purigen, phosphate out, etc)
end up with some filter wool to polish (alhtough I never do this)
Few months ago i bought a JBL e1500...
I took out the two trays with bio-ceramic balls and replaced them with blue spunges (tip: sometimes you can buy large mats of these blue spunges (1m x 1m) in the aquarium/pond shop = WAY cheaper!, just cut to size)
first; coarse blue spunge, ceramic pipes and purigen, more blue spunge (normally purigen would go on top, but lack of room there
)
the leftover ceramic balls (micromec), I put in my internal filter (the one that came with the Juwel 450 aquarium)
I just took the worn-out nitrate removing spunge, cut out a large circle in the centre, took a nylon sock from the missus and filled it with the micromec.
now my internal filter is just:
(in to out)
loose filter wool,
coarse blue spunge
micromec (4 layers)
fine blue spunge
Filter away