Its not the bulbs, its the lack of reflectors. That 150g that I linked you to is using a 3x250wattSE w/ 2x160wattVHO retrofit from hello lights... the reflector is nothing much more than a flat sheet of aluminum. Add to that the bulbs are about 12" above the water... no wonder he only has 200-300 at the very top of the tank. He could be getting away with only 150wattDE's if he had decent reflectors on them.
What are the dimensions of the tank? A standard 120g? 4'x2'x2'? The best lighting setup I have seen for 120s is the following...
2x250wattDE halides in reef optix 3 reflectors or PFO mini-pendants, and then 4x54wattT5s. The halides are 10,000Kish (XM 10,000K, Ushio 10,000K or 14,000K) and the T5s are a combo of 2 blue+ and 2 true actinics/super actinics. You will get PAR levels in the 300-500 range across the whole tank. I have never seen better results in a tank, PERIOD. The corals glow and grow like mad... impossible to reproduce with just T5s or halides alone.
IF you are talking a 6' long 120... like 72"x18"x22"h, then it gets tougher. I would suggest either going all T5 or all halide... its tough to scrunch both in to a tank that is only 18" deep and that long, since bulbs will most likely have to overlap. But it can be done 'creative'-like...
Only two 250wattDE bulbs there.
But SE bulbs... they are fat, take up more space, etc.
The other option is to go with only two rows of T5s... use something like 3x250wattDEs with only two rows of T5s... blue+ bulbs only. Thats a great combo.
OR just all T5s... something like 6x80watt T5 bulbs running on Icecap660 ballasts (slight overdrive to 100watts each, bright as all heck).