Some custom medias contain a variety of both auxins and cytokinins; and the addition of coconut water muddies that issue even further, since it already contains a variety of plant growth regulators (in addition to sugars, sugar alcohols, amino acids, purines, vitamins, etc). Also, both auxins and cytokinins, depending upon their concentration, type and plant species involved, can either serve to promote or inhibit, to some degree, one another.
Activated charcoal (use only a "pharmaceutical" or TC-grade) is solely from wood and is very absorptive of toxic substances in media -- such as phenols exuded from explants; and other compounds, for example, 5- hydroxymethyl-furfural (HMF), a product derived from sucrose through autoclaving media under acidic conditions; and to remove fatty acids from bacteriological cultures. The drawback is that it also removes promotory substances, especially auxins; charcoal also contains a small amount of PGRs; and it can raise the pH of media by .75-1.0. It is also used to minimize or exclude light from cultures to promote various dark-related functions, such as rhizogenesis (root formation), etc.
I have also used all manner of plant growth regulators and additives, including auxins, cytokinins, ethylene, gibberellins, phenols, polyamines, steroids; organic (citric, lactate, malic, et al) and abscisic acids, to name a few . . .
