Do not add chemicals the frogs will breath through there skin,for algae control you first have to discover why there is excess algae,cut down light times and food! I recommend you do not feed them every 3rd day and smaller portions atleast until the tank improves , but keep fasting them every 3rd or 4th day forever, clean up will take time unless you do a tank strip which is not recommended at this frail time* instead do 10% DAILY water changes during which turn off filter to prevent clogging then scrape some algae each day and siphon /hoover as much algae you can, it will take time don't go daft and try doing to much to quickly* for water temp just compare using the temp of tank water until you get gauge
live plants are a helpful solution as they compete with algae I will post a link to hardy plants