I would buy the 2x18w fixture any day of the week. Dismissing the Aqualight T5 because of the lower wattage is foolish.
In this case 65w of CF is very inefficient. Most of the light is bounced around, between bulbs, atop of the tank or inside the fixture. The bulb lights the tank with brute force. The size of the bulb is actually its hindrance. Such a large bulb blocks reflected light. The CF bulb is good in applications like a nano where 27w quad style bulb provides much more light coverage because of the size of the bulb.whats the difference between the CF and t5's (giesemann and aqualight) that makes 65w vs 24 or 36W so comparable?