02-08-2010, 02:31 PM
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For several years in the mid-1980's I had a 55g with one 48-inch 40w tube. It was a "Grolux" which was the rage then, in planted tanks. Very dim light by comparison to the full spectrum same size, and I didn't like the purplish hue it cast. I had thriving swords, and never fertilized. Though I did use magnesium sulfate once a week, on the advice of a planted tank aquarist writing a monthly column in FAMA at the time. It seemed to work fine.
I would suggest a single 48-inch tube to be preferable to two smaller tubes; reason being you have more even light distribution down the tank from end to end. Also, the less expensive full spectrum tubes are available in 48 inches and the other sizes are not, at least here at Home Depot, etc. May be different in the US so then that wouldn't be a consideration.
Last edited by Byron; 02-08-2010 at 02:33 PM..