My acans are abour 18 inches below my 6 bulb t5 set up. I have been debating moving them to the sand bed to try and get a bit of the yellow coloration they had back. Not sure if this is a good idea or not as they seem to be doing ok otherwise. I have only had them for about two weeks so I really can't say if they are "growing", I get good feeder extension though. I know if I leave them where they are they will be able to grow into a shaded area, which I hope will bring back that color as well, my issue is I have a 30 inch deep tank so the sand bed is very far away.