I agree with Thomas, but keep in mind the size of the tank. 13 watts on one of those .75 gallons would equal the same WPG as 1300 watts on a 75. But an anemone can live under the 1300 watts on the 75, but not the 13 watts on the .75. Of course, it won't be able to live long in such a small tank, but just leave that variable out in this example.