Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Activated carbon does not starve the plants.
Activated carbon has some affinity for some of the chelated forms of fertilizers. Usually iron is the only one dosed as a chelate. Read the label on whatever ferts you are using, see what form they are in.
Activated carbon usually reaches a saturation in just a few days, so even if it did remove some fertilizer the effect stops, so the plants are getting fertilizers until you add new AC.