Do floating plants like Salvinia really help with water quality?

Yes, according to r/PlantedTank discussion. Hobbyists describe floaters such as Salvinia minima as effective nutrient exporters, with one frequently upvoted sentiment being that a healthy mat of floaters does the work of a partial water change. The main caveats raised are that strong surface agitation from filters drowns the leaves, and the mat needs thinning so it does not block light to plants below.