whoa, that fast? is it ok to keep them on bottom? i know it depends on your lights, i have 8 bulb t-5 , i have a pink millepora about 3 inches above them that is colored nice, i figured if it gets enuff light ,these will be fine? i had to move my croceas up from bottom however............... reason i ask , placement on live aquaria says middle to upper of tank but i dont want them taking over...........