My tank is about 2.5 months old. It is 20 gallon, I have a pair of clownfish, a diamond watchman goby, a cleaner shrimp, and various corals. Hair algae is starting to grow. What can I add/do to get rid of it? I know lawnmower blennies eat hair algae, but is my tank too small? Will it get along with the diamond watchman goby?