Wrong choice of plecs. Both require high levels of oxygen coming from areas where rapids are abundant and considering your use of co2 i doubt you will have very high surface agitation, while they will not directly damage your plants they will break stems and uproot them with very little trouble. The gold nugget will dig it's own hide which will end up being your back corner by the look's. They will both fight and compete for food which will require you to feed each end of the tank, also being a plec they are renown for going without food becoming extremely under weight but from view-able positions looking healthy and fit. Both produce large amounts of waste that by the look's will not be removed by your filter, meaning constant manual removal. Heavy lighting will not be tolerated leaving relatively expensive fish reclusive. There overall size i would assume you have taken into consideration.
I don't mean to come off as overly aggressive but these facts will inhibit the growth of your plants and joy of your fish.