Does the watts per gallon rule applie to T-5 bulbs?

Okay, I have a 30 gallon aquarium with a hood that can fit one T-8 fluorescent bulb. Now I want live plants for it, low to medium light plants. So I ovioulsy need more watts. Now, I've heard the watts per gallon rule applies to T-8 fixture, but what about T-5 fixtures? I know T-5 lighting fixtures produce more Lumens per watt. So would a single 24 watt T-5 be better than a single T-8 20W? I'm going for mostly medium light plants... Would that do, a T-5 fixture for a 30 gallon aquarium, 24W?