I have my fish only tank with the store bought flourescent light in the hood; what are some hardy sessile inverts which don't require much light? I would be willing to upgrade the bulb in the fixture, but can't afford a new hi tech fixture and lighting right now. I've heard yellow colonial polyps dont require light, but then I've also heard that they do. I would like something pretty, hardy, and that will 'spread out.' (no aiptasia!) Any recommendations?