has anybody had any experience with one of these? ive heard they can be rather tricky. i have one and am trying to figure out whats best for it. initally i had it high in my tank and the polyps opened quite nicely. there wasnt alot of water movement up there. also a blue "coraline" started to spread over the beigey colored trunk. but heard they did better lower and with moderate water movement. i moved it lower and it doesnt look as good. any opinions or help is greatly appreciated.