Clowns Won't Come Out!!

[cicely]

Our two Tomato Clowns (matched pair, been together for 7 years) won't come out of the back of the tank. They hide in the reef, and won't come out except for when the pumps are shut off. We bought them a green bubble tip anemone, which has been in there for about 2 months, but they completly ignore it. What do we do???

 

[cicely]

Can we add a pair of Percula (sp?) clowns into the tank since the other clowns don't come out? The tank is 150 gallons, 6 ft long, 2 feet tall...