10gallon lightig confusion

A 13w compact fluorescent is considered 13w, even if it's equivalent to that of a 60w incandescent.
 
im confused. we have many compact flouresents throughout our home and the wattage that they use is between 13 and 23 watts. but the output on the 13 watter is 60 watts. so if i had a cf Using 13 watts, but Outputting 60 watts, wouldnt that be like 6 wpg on a ten gallon? just because they use 13 watts doesnt mean that their output is equal to that does it? thanks.

I asked the same question here...

http://www.aquariacentral.com/forums/showthread.php?t=136957
 
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