I would do 2 of these! I have them on my tank and they are great for the money! They are small but cover a very nice area!!
http://www.hellolights.com/index.asp...OD&ProdID=1325
and this, depending on what bulb kelvin you choose for the MH's (actinic supplement)
http://www.hellolights.com/index.asp...ROD&ProdID=231
Good luck!