look into enivrolights just search for it on the net their large CFL grow bulbs their about $49-$200 bucks depending on what wattage you get i have used the 125 watt full spec to veg 4-6 plants it works good i have flowered with it but it will only support two 2 ft plants and the buds are not very dense as for those 4 ft lights that you have their good for veggins your plants i put my plants about 1/2 inch under them they run pretty cool and then when my plants out grow them i stand them on their end and use them on the sides

good luck-Bomb