I've been running a 9 gallon tank with 2 clowns, and a goby/pistol pair, and even with weekly 1 gallon water changes, using purigen, and a refugium, the hair algae is beginning to get bad in the tank. It won't be much longer, and I'm going to have to get the clowns out of the tank, as it just won't maintain the way it is. It has been a slow process of getting worse and worse, but I knew when I put the clowns in the system that it probably wouldn't be long term. Good luck with your system.

Damsels arn't all that bad.

I have an azure damsel (one of the first fish in the tank) getting handled by a purple firefish (the last fish in the tank) ..and this is a 150 gallon aquarium