I've been keeping some arcopora birdsnest under my 4 X54w t5's. I do keep them towards the top though and they are growing really really well. The one has quadrupled in size over 2 months.
i also have brand new ATI bulbs in my bad boy. lol
edit** The ro
unit was really cheap that was a concern for me but it's working out real well. The replacement filters are $19 for the 3 and I think $50 for the three and the DI
filter. So it's almost cheaper to buy a new one when the filters go out. Make sure you have a tds
meter so you can tell when that happens if you invest in the unit.