My understanding, as it has been explained to me by my team in Germany, is that most (not exclusively but most) of the algae and bacterial critters that we would prefer NOT to grow in our systems, have much better mechanisms for utilizing monomers than anything that is longer carbon chains. They just don't have good ability to break those longer chains down to the monomers they need. While the good guys (algae and bacteria) that are helpful to us have much better mechanisms for breaking those longer chains down to the monomers they utilize. So if you add mostly carbon chains that are more than monomers, you "target" and focus that nutrition on the beneficial critters we like to see multiply and help our closed tank system biome.