Have a 25 gal. nano tank that's been running for over 5 years. It has been filled with Tonga rock and has two soft corals, mushrooms and two small clown fish. All are doing well.The Tonga rock is covered with a brown growth and is difficult to keep clean. I use Chem Blue and activated carbon. I've used Phosban in my reactor without success. I'm looking for something to use in the reactor that might help with the brown algae that covers the rock. I do monthly water changes. I also have a small skimmer. Any advice is appreciated.