start by getting your fish elsewhere! you might have top travel a bit more but is it worth risking all the fish in your tank getting sick? Do you have a hospital tank? or are you treating your main tank?
how much of the water do you change? I had black beard algae, tried everything no lights. no food, flourish, peroxcide. The only thing that really made a big difference was big water changes. Like half for a few weeks in a row. Good luck