[ReeferNoob4ever]

In my experience Duncans are pretty tough. I have one that opens and closes as it pleases but over the past 6 months or so has gained 8-10 heads. I wouldn't worry about it unless it sucks itself in and stays like that for weeks. Otherwise they sometimes shrink to poop (you will see the brown stuff coming out of their mouths) or just because. I also have T5 lights and went I tried LED out for a few it was not happy. I put back on my T5's and it's good as new.