Hi all. I have a fluval evo 13.5g I've been running it now for over a year. All has been well until a month ago when zoas wouldn't open. I've had some hair algea which I'm dealing with. I'm doing regular water changes and just introduced some chemi pure into the sump. All my parameters are fine and everything else in the tank is looking good. Any advice would be good. Thanks. Also I'm starting to get bubbles coming up from the sand during the evening.