Rookie mistake. I bought this Duncan not long after setting up the tank because I heard they were "easy".

Those 2 bleached branches were there when I bought it. Stupidly, I superglued it to the main rock before I realised it should have sat lower in the tank. Until now, it only extended it's polyps when the lights were off at night (normal) and before the lights were on in the morning in ambient light.

Finally, I think it has adapted to the light conditions and starting to enjoy life.