I think he is talking about 4X ODNO.. what is the ballast type? 4-F32T8 or a Fulham WH5 maybe? and are you using 1 ballast per bulb (all 4 power leads to each bulb)? the output of the NO
bulbs at 4X ODNO is roughly 100-125 watts worth of lumens *edit*assuming your using 48" T-8 bulbs*edit*.. I would suggest 4 or 5 of them.. getting bulbs that would be approprate for a reef tank in NO
might be difficult IMO
.. you might be able to get enough light intensity but it might be the wrong color.. and another question.. what bulbs are you using are they T-8's or T-12's?
*edit* my bad.. your using 36" lamps... you will likely need 6 and 6 ballasts DIY CF
would be cheaper.. unless your getting the 4-F32T8 ballasts for less then $20 *edit*