Just picked one of these up from my LFS. i know they don't like light and like flow but mine only seem to open up when i feed and even then it not all the way? Any suggestion? water s in good condition. 1 gal water changes about every 3 days.(out of 6 gal nano) lighting is 2x18 watt T-5. coral in out of direct light and in good flow. Do they need Dark? any help would be great.