definitely use the hps bulbs. they are more energy-efficient, and will use less space and maintenence than a collection of tubes. plus i believe its a better spectrum

(based on knowledge of t8 and t12 bulbs. no idea if applies to t5 as well)

also, assuming that your only growing the same set of plants, you can get either a switchable ballast or conversion bulb and use mh light to veg under with the same socket.


600w may be a bit over the top for only 2 plants though. how long are you planning to veg?