On my 29 gal I have an AH retrofitted 55W, with their reflectors and a plain 20W strip - the type that comes with the tank. They sit on a glass top with the 55W to the back, the 20 to the front. When I turn on and off the 20W, the difference in the illumination of the tank is minimal. So I was wondering, you plant physiologists out there, how much benefit the 20W is actually providing for the plants? Are the chloroplasts and photosynthesizing machinery actually benefitting from the extra 20W, all things being equal?