Bill Beam wrote in message . ..
Is a watt a watt? I was told by a dealer that the compact smartlite
is a lot more intense so I don't have to follow the 2.5 watts per
gallon rule to grow plants. Is this true?

Different lights do vary a lot in how much you get for a watt. In
general, any fluorescent using an electronic ballast will outperform a
fluorescent using a magnetic ballast, even if it's the exact same
bulb.

Beyond that, thinner tubes tend to have higher performance. T5s do
better than T8s do better than T12s.

I don't know what the smartlite is, but assuming it's an
electronically-ballasted compact fluorescent, it may well be more
intense. But then, the 2.5 watts per gallon rule is bunk anyway.

- Jim