I looked up the Brightwell's product, and to me it sounds like good rinsing will do it. The information on the product, of course when used according to directions, states to add more snails for CUC while using the product. So when used properly, not toxic. So any residuals left over after rinsing would not be a concern for me.
Copied from amazon's listing:
"Used as directed, it is safe for marine fishes, hard and soft corals, and other inverts, as well as most macro-algae, however, as all animals are individuals, and water conditions vary in many aquariums, animals should be observed closely during use, for signs of stress (corals closing and not re-opening, erratic behavior etc.). If signs of stress occur, or if macro-algae are affected negatively, reduce or discontinue use as necessary. If symptoms persist, do a partial water change and add carbon."
Copied from amazon's listing:
"Used as directed, it is safe for marine fishes, hard and soft corals, and other inverts, as well as most macro-algae, however, as all animals are individuals, and water conditions vary in many aquariums, animals should be observed closely during use, for signs of stress (corals closing and not re-opening, erratic behavior etc.). If signs of stress occur, or if macro-algae are affected negatively, reduce or discontinue use as necessary. If symptoms persist, do a partial water change and add carbon."